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: