Blender Git Loki

Fix T49489: Pose marker in camera action + marker bound to camera -> crash.

'camera' Object pointer of TimeMarkers is a 'temp' hack since Durian project...
Would need to be either made definitive now, or removed/reworked/whatever.

But since we intend to use that object pointer for other needs, and current code
could lead to crashing .blend files, for now let's fix that mess (was missing
some bits in read code, and also totally ignored in libquery code).

Should be safe for 2.78a.