CMake: add definition KICAD_TESTING_VERSION and KICAD_STABLE_VERSION.
One of these 2 options *must* be now defined (i.e. run cmake with option -DKICAD_STABLE_VERSION or -DKICAD_TESTING_VERSION
Stable and testing branches should be more easier to maintain.

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

* store selected language by name instead of wx language id (that changes between wxWidgets version)
* accept always comma and point as flotating point separator.

fix 2 minor bugs: GERBVIEW: Button "Erase all layers" not working, EESCHEMA: Plot to Clipboard: EDA_DRAW_FRAME::PrintPage() error

Pcbnew: dialog plot: make message window resizable, add tool tip and remove unused sizers.

Commit installer translation files for Japanese

Pcbnew, Module Editor: fix bug 707692 and other potential crashes (when having a block command in progress and try to make an edit command)

This was due to a duplicate constants ( with sligtly different values)  used to select items in some seach functions that broke filtering. Old definitions removed.

Pcbnew: fix that prevents loading modules from libraries (footprint name not identified in lib)
Module Editor: Try to fix incorrect printing. Fixed now only for scale 1. Nor working for other scales. (Work in progress).
Gerbview: Known bug: printing not working.
VRML export: Fix incorrect export of 3D shapes rotations when the 3D shape was rotated.

fixed others very minor bugs.

All: fixing a recent problem when using scroll bars: the full screen was redrawn, that can be very slow in Pcbnew.