Pcbnew: fix Bug #1373468 (Non Copper Zones Properties  dialog "Layer selection" empty) (Linux specific)

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.

Minor change: Eeschema+Pcbnew: display timestamp in edit dialogs (for footprints, sheets, components)

Fix an annoying issue about not named nets:
now, these nets are named from the component references and pin names which are connected.
therefore, unless the net or the footprint references are modified, the net name is not modified between 2 netlist calculations.

Pl_Editor: fix copyright in files. Enhancement when creating new items.

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

Fix rounding issue when a double is stored in a wxConfig file (wxWidgets 2.9.4 store only 4 digits in mantissa).
A new inline function ConfigBaseWriteDouble( config, key,  double_value )  is used instead of config->Write(  key, double_value ) which store 12 digits

Eeschema: fix bug 1082107 (error message" component not found" when no component selected from select component dialog box)

This is *a work in progress*, so some features are missing, and/or could be modified.
Mainly keepout zones are not yet exported to autorouters, and pads are not taken in account.
Some code cleanup in polygon.*

Fix incorrect import of smd pads from Gpcb.
Very minor change in dialog print.

All: fix a truncation issue in ReturnValueFromString that creates sometimes a small error for values entered in dialogs.
Pcbnew: fix a compatibility issue with nano version for zones parameters.

autoroute functions: code cleaning

* Derive the pcbnew copper zone and non-copper zone dialog windows from DIAG_SHIM,
  which injects some template code.
* Update UIpolicies.txt to talk about DIALOG_SHIM support.
* Add zone support to eagle_plugin.
* Organize ZONE_CONTAINER class declaration for future privacy and accessors.

* 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.

* 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.

* EDA_DRAW_FRAME completely encapsulated except for DrawFrame member.
* Moved members specific to Pcbnew from EDA_DRAW_FRAME to PCB_BASE_FRAME
  or PCB_EDIT_FRAME as appropriate.
* Replace EDA_TOOLBAR with wxAuiToolBar as EDA_TOOL bar provided no
  additional functionality and made code less readable.
* Remove EDA_TOOLBAR class definition from wxstruct.h and delete file
  wineda_toolbar.cpp.
* Rename tool bar members to something more descriptive since the
  horizontal and vertical references wont mean anything once the
  tool bars are movable.
* Lots of dead code removal.

* Correct all user strings and comments for the correct capitalization of
  application names according to JP.  They are KiCad, Pcbnew, CvPcb,
  Eeschema, and GerbView.
* Add a note the the user interface policy about the correct capitalization.

* All header files used to create the PCB common library now compile as
  stand alone code.  This prevents the need to define them in a specific
  order to make source code compile properly.  It should also now be
  possible to relocate the source code to build the common PCB library
  to a separate folder.