Removing Blender Game Engine from Blender 2.8

Folders removed entirely:
* //extern/recastnavigation
* //intern/decklink
* //intern/moto
* //source/blender/editors/space_logic
* //source/blenderplayer
* //source/gameengine

This includes DNA data and any reference to the BGE code in Blender itself.
We are bumping the subversion.

Pending tasks:
* Tile/clamp code in image editor draw code.
* Viewport drawing code (so much of this will go away because of BI removal
  that we can wait until then to remove this.

build_files/cmake/config/blender_headless.cmake

@@ -6,7 +6,6 @@
 #
 
 set(WITH_HEADLESS            ON  CACHE BOOL "" FORCE) 
-set(WITH_GAMEENGINE          OFF CACHE BOOL "" FORCE)
 
 # disable audio, its possible some devs may want this but for now disable
 # so the python module doesnt hold the audio device and loads quickly.