Add LLMotionController* LLMotion::mMotionController

This is needed for synchronization: motions will have to start
(with a specific start time offset) from a point in the code where
only the motion object is available.

I added/used LLMotionController& in a previous commit, this was
now changed into a pointer. There is (obviously) not much reason
for that, but also no disadvantage: the diff relative to LLs code
doesn't get larger since the references where already added, too.

Conflicts:
	indra/llcharacter/llkeyframemotion.cpp
	indra/llcharacter/llkeyframemotion.h

indra/llcharacter/llhandmotion.cpp

@@ -61,7 +61,7 @@ const F32 HAND_MORPH_BLEND_TIME = 0.2f;
 // LLHandMotion()
 // Class Constructor
 //-----------------------------------------------------------------------------
-LLHandMotion::LLHandMotion(LLUUID const& id, LLMotionController& controller) : AIMaskedMotion(id, controller, ANIM_AGENT_HAND_MOTION)
+LLHandMotion::LLHandMotion(LLUUID const& id, LLMotionController* controller) : AIMaskedMotion(id, controller, ANIM_AGENT_HAND_MOTION)
 {
 	mCharacter = NULL;
 	mLastTime = 0.f;