Fixed|Input: Don't pass invalid events to the game

Some events do not have a game-side equivalent, so those should not
be passed to the game via any responder.
Stereo 3D|Oculus Rift|Client|Renderer: Modify TODO comment
Merge branch 'oculus-rift' of https://github.com/skyjake/Doomsday-Engine into oculus-rift