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)

Some minor code cleaning.

* 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.

* 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.

Fix minor issues.
Fic compil issue in dimension.cpp with wxMSW 2.8.12 (wxMSW 2.8.12 only).

Remove obsolete foldr resources/icons.
Updates svg icons in folder resources.

* Refactor locate footprint function into the board object.
* Remove locate.cpp as it is no longer needed.
* Actually remove track.cpp from repo that I missed on the last commit.
* Increase the size of the layer pair tool bar bitmap so that it looks
  better with the new larger tool bar images.
* Fixes to prevent common headers from complaining when not included
  in the correct order in source files.

* Refactor trace mark functions into the board object.
* Remove track.cpp as it is no longer needed.
* Dead code removal.

* Refactor trace search functions into the appropriate object.
* Translate French code names and comments.
* Lots of coding style policy fixes.

* Refactor pad locate code into the appropriate object.
* Dead code removal.
* Lots of coding style policy fixes.

* Refactor via locate code into the appropriate object.
* Rename all HightLight code to HighLight.
* Dead code removal.

* Move various locate functions into the appropriate board item object.
* Unified best zoom for all frames derived from PCB_BASE_FRAME.
* Remove track.cpp as it is no longer needed.
* Dead code removal.
* Remove scary frame window pointer member from board item objects.
* Add draw bounding box to gerber draw item for debugging purposes.

* Changed <wx-2.8/xml/xml.h> to "xnode.h" in pcbnew_config.cpp to fix bug
  when building against wxWidgets 2.9 and above.
* Convert broken wxXmlNode code to use XNODE.
* Overloaded XNODE constructor for creating child nodes.
* Translate French naming conventions.
* Translate French comments.
* Remove tabs from several source files.
* Coding style policy and Doxygen comment fixes.

* Rename all ADD_MENUITEM_* functions to AddMenuItem and move them to
  wxstruct.h since they are used by the Kicad main frame classes.
* Move SET_BITMAP and SETBITMAPS definitions to wxstruct.h.
* Fix a bug in SET_BITMAPS that prevented enabling menu item images on
  OSX.
* Rename MsgItem to EDA_MSG_ITEM.
* Remove redundant includes from modified files.
* Doxygen and coding style policy fixes.

Pcbnew: finish work on Length Die (displays track length, and fulll  length and length die for tracks ending on pads having a length die > 0 )

* Fix grid select box update bug on context menu.
* Fix via size and track width select box update bugs.
* Fix layer pair indicator button update bug.
* Fix auto track width tool bar control enable bug.
* Fix via size and track width select status bug in context menu.
* Fix layer select box and layer control widget select bug when current
  layer is removed.
* Add virtual function to notify objects derived from EDA_DRAW_FRAME that
  the units setting has changed.
* Coding policy class naming fixes.

* Changed managed cursor callback definition to include the current
  cursor drawing position.
* Modified all managed cursor callbacks to match new definition.
* Added snap to grid option to base drawing frame object.
* Changed add no connect managed cursor callback to use new position
  parameter instead of the stored one.
* Lots of coding policy fixes.

* ActiveScreen global variable is gone, yeah!
* Use drawing coordinates instead of screen coordinates when calling
  GeneralControle().

* Use wxDC to calculate screen center position.
* Minor grid drawing optimization.
* Remove an unnecessary use of global variable ActiveScreen.
* Doxygen warning fixes.

* Remove all occurrences if #ifdef USE_WX_ZOOM and all associated code within
  the #else/#endif block ( old zoom code ).
* Removed the build option for USE_WX_ZOOM from CMakeList.txt and config.h.in.
* Removed all scaling code in base screen object.
* Fixed buffered paint and buffered client DC on Windows.  Buffering works
  properly on Linux and Windows.
* Modified kicad_device_context.h to automatically uses buffering on platforms
  where double buffering is supported natively.
* Remove all of the scaled versions of the drawing functions in gr_basic.cpp
  and any support code.
* Removed all traces of ActiveScreen global variable from eeschema and
  gerbview.
* Renamed Recadre_Trace to RedrawScreen in draw frame object.
* Renamed PostDirtyRect to RefreshDrawingRect in draw panel object.
* Lots of code cleaning an Doxygen comment improvements.

* Move schematic wire and bus break code into schematic screen object.
* Move schematic test for dangling ends into schematic screen object.
* Remove left over debugging output in schematic screen object.
* Remove unused file eeschema/cleanup.cpp.
* Fix bug in schematic line object hit test algorithm.
* Fix a string concatenation compile error added in r2752.
* Rename class WinEDA_BasicFrame to EDA_BASE_FRAME.
* Rename class WinEDA_DrawFrame to EDA_DRAW_FRAME.
* Rename class WinEDA_DrawPanel to EDA_DRAW_PANEL.

can be deleted later if they exist in the headers, or moved to 
headers if they should exist in the headers.

Added hotkeys editor from David Turner, with a lot of enhancements and fixes
Added pins connections info in intermediate netlist for each compoment. This is redundant, but some netlist formats (ORCADPCB, PSPICE) are very easy to create with this redundant info.

removed global variables and a lot of redundancies

Pcbnew :added option to show/hide footprints values and/or references

Removed old color and visiblity dialog
work in progress.
See also TODO, P0)

* Complete comment translation of PCBNew source.
* Some tooltip capitalization fixes in PCBNew toolbars.