Eeschema, Plot dialog: add Plot directory selection. The patch from 1383026@bugs.launchpad.net was widely used.

  *) When kicad.exe closes a project, close any open KIFACEs so that they cannot
     get disassociated from their true PROJECT.
  *) Allow loading eeschema library editor from kicad.exe
  *) Allow loading pcbnew library editor from kicad.exe
  *) Rename LIB_COMPONENT to LIB_PART.
  *) Add class PART_LIBS, and PART_LIB.
  *) Make PART_LIBS non-global, i.e. PROJECT specific.
  *) Implement "data on demand" for PART_LIBS
  *) Implement "data on demand" for schematic SEARCH_STACK.
  *) Use RSTRINGs to retain eeschema editor's notion of last library and part being edited.
  *) Get rid of library search on every SCH_COMPONENT::Draw() call, instead use
     a weak pointer.
  *) Remove all chdir() calls so projects don't need to be CWD.
  *) Romove APPEND support from OpenProjectFiles().
  *) Make OpenProjectFiles() robust, even for creating new projects.
  *) Load EESCHEMA colors in the KIWAY::OnKiwayStart() rather in window open,
     and save them in the .eeschema config file, not in the project file.
  *) Fix bug with wxDir() while accessing protected dirs in kicad.exe
  *) Consolidate template copying into PROJECT class, not in kicad.exe source.
  *) Generally untangle eeschema, making its libraries not global but rather
     held in the PROJECT.

Pcbnew: Commit patch (with very minor changes) about SVG file export with the layers ordered from bottom to top. ( bug 1286646 ), from Thiadmer Riemersma.

2) Change from legacy Cu stack to counting down from top=(F_Cu or 0).
   The old Cu stack required knowing the count of Cu layers to make
   sense of the layer number when converting to many exported file types.
   The new Cu stack is more commonly used, although ours still gives
   B_Cu a fixed number.
3) Introduce class LSET and enum LAYER_ID.
4) Change *.kicad_pcb file format version to 4 from 3.
5) Change fixed names Inner1_Cu-Inner14_Cu to In1_Cu-In30_Cu and their
   meanings are typically flipped.
6) Moved the #define LAYER_N_* stuff into legacy_plugin.cpp where they
   can die a quiet death, and switch to enum LAYER_ID symbols throughout.
7) Removed the LEGACY_PLUGIN::Save() and FootprintSave() functions.
   You will need to convert to the format immediately, *.kicad_pcb and
   *.kicad_mod (=pretty) since legacy format was never going to know
   about 32 Cu layers and additional technical layers and the reversed Cu
   stack.

!   The initial testing of this commit should be done using a Debug build so that
    all the wxASSERT()s are enabled.  Also, be sure and keep enabled the
    USE_KIWAY_DLLs option.  The tree won't likely build without it.  Turning it
    off is senseless anyways.  If you want stable code, go back to a prior version,
    the one tagged with "stable".

*   Relocate all functionality out of the wxApp derivative into more finely
    targeted purposes:
    a) DLL/DSO specific
    b) PROJECT specific
    c) EXE or process specific
    d) configuration file specific data
    e) configuration file manipulations functions.

    All of this functionality was blended into an extremely large wxApp derivative
    and that was incompatible with the desire to support multiple concurrently
    loaded DLL/DSO's ("KIFACE")s and multiple concurrently open projects.
    An amazing amount of organization come from simply sorting each bit of
    functionality into the proper box.

*   Switch to wxConfigBase from wxConfig everywhere except instantiation.
*   Add classes KIWAY, KIFACE, KIFACE_I, SEARCH_STACK, PGM_BASE, PGM_KICAD,
    PGM_SINGLE_TOP,
*   Remove "Return" prefix on many function names.
*   Remove obvious comments from CMakeLists.txt files, and from else() and endif()s.
*   Fix building boost for use in a DSO on linux.
*   Remove some of the assumptions in the CMakeLists.txt files that windows had
    to be the host platform when building windows binaries.
*   Reduce the number of wxStrings being constructed at program load time via
    static construction.
*   Pass wxConfigBase* to all SaveSettings() and LoadSettings() functions so that
    these functions are useful even when the wxConfigBase comes from another
    source, as is the case in the KICAD_MANAGER_FRAME.
*   Move the setting of the KIPRJMOD environment variable into class PROJECT,
    so that it can be moved into a project variable soon, and out of FP_LIB_TABLE.
*   Add the KIWAY_PLAYER which is associated with a particular PROJECT, and all
    its child wxFrames and wxDialogs now have a Kiway() member function which
    returns a KIWAY& that that window tree branch is in support of.  This is like
    wxWindows DNA in that child windows get this member with proper value at time
    of construction.
*   Anticipate some of the needs for milestones B) and C) and make code
    adjustments now in an effort to reduce work in those milestones.
*   No testing has been done for python scripting, since milestone C) has that
    being largely reworked and re-thought-out.

*) add hotkey for setting the grid origin as 'S', in board editor, module editor.
*) re-position the function interface for cursor movement from BASE_SCREEN into
   class EDA_DRAW_FRAME.  This is a prelude to getting rid of BASE_SCREEN or
   splitting it up.

New conversion routines and sin/cos implementation for angles in decidegrees

Implemented the LAYER_NUM typedef (LAYER was already taken as a class name...) to represent a layer number.

- Renamed ReturnMaskLayer to GetLayerMask (since it's a plain getter)

standard layer name support from BOARD::GetLayerName().  This function evolved
in a contorted direction over time, and was being asked to return one of 3
different kinds of layer names, even though it only took a boolean to control
that choice.  

Users are better served by forcing them to get to know the concise new 
English Standard layer names.  This is because these concise names show up
in the "pretty" footprint/module files as the standard representation of
both feature and copper layers.

Change the name of BOARD::GetDefaultLayerName() to GetStandardLayerName().
Drop boolean argument to both BOARD::GetStandardLayerName() and 
BOARD::GetLayerName().

Pcbnew, plot functions: fix bug in SVG plotter, fix a minor other bug when using PS plotter (trcak width fine adjust not working)
and plot code cleaning continued

All: remove macros  MAX, MIN, ABS from macros.h and replace these macros by std::max, std::min and std::abs (mainly found in old code).

dcsvg (and therefore KicadSVGFileDC)  is now unused. Use SVG plotter only to export a board SVG file.
SVG export does not use no more wxWidgets wxDC.
In pcbnew SVG files can be created by plot menu (in B&W) or export SVG menu (B&W or Color).
Export SVG menu is more suitable to create a view of a board, and plot menu is better to create a B&W document of silkscreen layers.
(In the future, the 2 menus could be merged, because they are not very different).
Note: pcbnew plot code is cleaned, mainly in dialog files, but still needs more cleanup.

Mainly to plot drill maps, but can be used to plot boards, for documentation.
The print svg still exists, but the plot SVG has more options (mirroring, holes in pads),
however  print svg allows color print, and full board printing, and plot does not.

dialog plot functions: fix compil warnings with wxWidgets 2.8

All: change MILS_TO_IU_SCALING_FACTOR constant to IU_PER_MILS ( and MM_TO_IU_SCALING_FACTOR to IU_PER_MM)
Also fix bug 985654.

All: change MILS_TO_IU_SCALING_FACTOR constant to MILS_PER_IU  ( and  MM_TO_IU_SCALING_FACTOR to MM_PER_IU)
Also fix bug 985654.

Other scaling factors (MILS_TO_IU_SCALING_FACTOR and DECIMILS_TO_IU_SCALING_FACTOR)
also defined only in convert_to_biu.h.
Allows different scaling value for Gerbview.
Needs more tests.

* Remove internal units from BASE_SCREEN and it's derivatives.
* Remove internal units from EDA_DRAW_FRAME and it's derivatives.
* Use build time code to replace internal units conversions.
* Fix scaling bug in page layout sample window that I created in my
  last commit.

* Move all convert from user to internal units into base_units.cpp.
* Remove internal units parameters from all moved conversion functions.
* Revise all source code that calls the moved conversion functions.
* Remove internal units from all dialog text control helper classes.

* Scale page reference border and title block, grid sizes, and zoom factors
  correctly for nanometers.

* Move all convert from internal to user units functions into separate file.
* Remove internal units parameter from all moved conversion functions.
* Revise all source code that calls the moved conversion functions.
* Compile these conversion routines separately for the appropriate pcb or
  schematic internal units.
* Move internal units specific status bar update code into the appropriate
  application for updating the status bar.
* Move millimeter user units rounding function to common.cpp.

wxWidgets 2.9 knows wxSVGFILEDC device context.
Unfortunately, arcs are drawn as pies (this is a feature, not a bug).
This is not correct for Kicad.
So Kicad has its own wxSVGFILEDC (named KicadSVGFileDC) that is basically the same as wxSVGFILEDC,
but with arcs drawn as arcs, not pies.
Note also under wxWidgets 2.8 does not know wxSVGFILEDC , so kicad had already its own SVG device context.

* EDA_DRAW_PANEL completely encapsulated.
* Moved OSX m_overlay member from EDA_DRAW_PANEL to EDA_DRAW_FRAME where
  it is used.
* Doxygen comment warning fixes.

* EDA_DRAW_FRAME completely encapsulated.
* Encapsulate the the low hanging fruit in EDA_DRAW_PANEL.