Note: We should test if the armature is the "armature modifier" parent of the
object.
If any good samaritan feels like tackling this, the function to change
is: DRW_pose_mode_armature
In the future this will allow us to implement things like face manipulators.
For now however, this is getting on the way of using pose mode
(mesh objects are drawn green).
NOTE: pose engine should also be the one taking care of pose bones
(and for that matter, X-Ray armature option should/could be a property
of the Pose engine even).
Same as MEM_SAFE_FREE macro,
checks for NULL, runs free then sets NULL.
Blocks of code that do this many times are noisy and likely
errors here wouldn't be noticed immediately.
Also NULL's static vars which were being left set.
This removes MAX_STORAGE, MAX_BUFFERS, MAX_TEXTURES, MAX_PASSES limits.
Actual memory saving isn't so important, it just means we don't need to
manually bump these based on changes to engines.
