Initial child entity code.
Network protocol support for entity parenting.
Fixes to entity parenting code. Switch the entity's parent in the 3d scene when parent changes.
Fix syncmanager listening to entity parent change.
Correct the attribute order of EC_RigidBody to match native Tundra. Closes #33.
Merge branch 'hierarchicscene' into dev

Conflicts:
	src/scene/EC_Placeable.js
Fixed UpdateTransform function.
Merge branch 'dev' into avatar
Added avatar example to repo.
Return child entity after creating it.
Updated EC_Avatar to use new entity parent child hierarchy.
Merge branch 'dev' into avatar
Added missing includes to xml3d examples.