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_app_handlers.c

@@ -59,8 +59,6 @@ static PyStructSequence_Field app_cb_info_fields[] = {
 	{(char *)"load_post",         (char *)"on loading a new blend file (after)"},
 	{(char *)"save_pre",          (char *)"on saving a blend file (before)"},
 	{(char *)"save_post",         (char *)"on saving a blend file (after)"},
-	{(char *)"game_pre",          (char *)"on starting the game engine"},
-	{(char *)"game_post",         (char *)"on ending the game engine"},
 	{(char *)"version_update",    (char *)"on ending the versioning code"},
 
 	/* sets the permanent tag */