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.

source/blender/python/intern/bpy_rna_callback.c

@@ -170,7 +170,6 @@ static eSpace_Type rna_Space_refine_reverse(StructRNA *srna)
 	if (srna == &RNA_SpaceNLA)              return SPACE_NLA;
 	if (srna == &RNA_SpaceTimeline)         return SPACE_TIME;
 	if (srna == &RNA_SpaceNodeEditor)       return SPACE_NODE;
-	if (srna == &RNA_SpaceLogicEditor)      return SPACE_LOGIC;
 	if (srna == &RNA_SpaceConsole)          return SPACE_CONSOLE;
 	if (srna == &RNA_SpaceUserPreferences)  return SPACE_USERPREF;
 	if (srna == &RNA_SpaceClipEditor)       return SPACE_CLIP;