Rework on env. variable KISYS3DMOD. Until now, was used in different files using different ways, so no consistency between files.
code cleanup.

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.

Better description for entities on right click menu and panel
Typo fixes and some comment reformats

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)

All: added a standard exit dialog called by int DisplayExitDialog( wxWindow* aParent, const wxString& aMessage )
Called when closing pcbnew, cvpcb and eeschema.
Minor code cleaning: remove duplicate or not used strings (mainly file extensions and wildcards)

 * Fix compil issue about automatically created pcb_plot_params.h :
     pcb_plot_params.* moved from pcbnew to common because item_io.cpp (using this file) is compiled in common.

* Move auto save time global variables into PCB_EDIT_FRAME object.
* Move footprint library name list global variable int PCB_EDIT_FRAME
  object.
* Improve library back up and temporary file error message strings and make
  them translatable.
* PCBNew string unification.
* Translate French code names and comments.
* Coding style policy and Doxygen comment fixes.

* More common header file compiler fixes.
* Translate French code naming and comments.
* Remove global variable ScreenPcb.
* Dead code removal.

* 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.

* Add hotkey "P" - place item
* Add record and play macros for sequence hotkey.
Macros set to numeric key 0..9.
<Ctrl>+<numkey> - start record macros
<hotkey> <mouse move> ... <hotkey>|<mouse place>
<Ctrl>+<numkey> - end record macros
<numkey> - play macros
* Add menu save/read macros to/from xml-file
* Add configure rotate angle for rotate module: 45 or 90 deg.
* fix segfault when move/drag segment if disconnected to pad

fix an issue created by commit 2954. Gerbview: display now an indicator of layers in use. minor code cleanup.

* Fix a minor problem with wxFileDialog to open a file that no longer
  exists in PCBNew.
* Make GerbView open file behavior the same as PCBNew.
* Remove redundant PCB file wild card definition.
* Add open file refactor task to the todo list.
* Fix some minor code formatting issues.

removed global variables and a lot of redundancies

hide/show rastnest in pcbnew is currently not working, will be fixed soon

* Split out application specific command IDs to prevent unnecessary rebuilding.
* Eliminate duplicate menu and tool bar command IDs.
* Split component library editor and viewer definitions to separate header files.
* More component library and document file merge code.
* A bunch of minor string readability and consistency fixes.

pcbnew: Starting work on undo/redo in pcbnew. Only some delete item commands are stored in undo/redo stack

Global variable unobfuscation, new library path search, and lots of other changes.  See CHANGELOG.txt.