Temporary fix a crash I created in rev 5427, when erasing all modules on a board and read the netlist. Will be fully fixed later.
Very minor fixes: remove duplicate #define in vrml_v2_modelparser.cpp, and "undo" a very minor change I made in class_board.cpp when I tried to fix a Pcbnew crash.

Pcbnew: fix  Bug #1422093 (pcbnew crashes after editing a footprint cominng from the board  with the fp editor and saving it on a librray and trying to load it to the board)
Some other very minor fixes.

* Add support for VRML DEF coordinate key word.
* Coding policy fixes by Blair Bonnett <blair.bonnett@gmail.com>
* Debugging output clean up.

Pcbnew: fix Bug #1413701 (Segfault on highlight "unconnected" net 0 in Pcbnew ). Also, remove now useless code and other very minor fixes.

Cleaning 3 svg files (no icon change)
Very minor other changes.

Eeschema: add dialog libedit options and move options relative to libedit from eeschema options to this dialog.
Ensure some values initialized by the schematic editor and used by libedit are also initialized in libedit even if  the schematic editor was not started.
Remove useless commands (save/load project config) in libedit, because now they have no sense.

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

Add patch from Mario Luzeiro to 3D viewer. Fix a serious issue due to duplicate ID used in menus and toolbars between sub-applications, related to wxUpdateUIEvent events loop.
wxUpdateUIEvent events can be sent to parent frames, when opening a menu in a child frame, if parent and child frame share same ID fro menuitems (or tools)
The wrong menuitem can be used in some cases ( because there are more than one menuitem with the same identifier), by a wxUpdateUIEvent event function run in a parent frame.

3d viewer: fix a (minor) bug when run from cvpcb or modedit: the footprint is now centered on Z axis
Better setup for lights, which gives a better rendering

3dviewer: back to double (from float) in class S3D_MASTER for 3 members (m_MatScale, m_MatRotation, m_MatPosition) which are used in dialogs and r/w file functions, which expect double.
Using float create minor but unwanted issues in  r/w file functions.
S3D_MATERIAL: enable all color options: if a 3d shape has bad color parameters, the shape must be modified, not the 3d rendering.
The rendering now matches what we see in other vrml viewer like FreeCAD.
Some minor coding style fixes.

3D viewer: move helper functions from 3d_draw.cpp to 3d_draw_helper_functions.cpp. Add comments in .h sources. Better management of background color. coding style fixes.

dialog_track_via_size: set minimal size  and make dialog resizable.
Update demo file.

3d viewer: Add high quality mode option is realistic mode (Shows holes in copper zones, but with longer calculation time)
Gal: fix a very minor issue: the keys to switch between copper layers are now - and + (according to the doc and the normall mode), instead of - and =

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.

This workaround was already used (bzr 4301, in file plot_board_layers.cpp) also to avoid similar crashes (uses 18 segments instead of 16 to approximate a circle by segments).
Minor code cleanup in dialog_plot.