This commit implements more of the CopyPose capabilities in
Blender. It is now possible to select which axis will be
constrained in position and orientation to obtain
interesting effects. Another option selects if the axis
are relative to the end effector or to the target.
Unlocking a position axis means that the coordinate along
this axis is not constrained and can take any value.
Unlocking the Y axis of the End Effector produces an
'aiming' effect: the end effector is oriented towards
the target but without stretching.
Unlocking a rotation axis means that the end effector can
freely rotation along that axis. Unlocking the Y axis
produces a 'tangent' effect: the end effector aligns with
the Y axis of the target but can rotate along that axis.
A 'floor' effect is possible if the position Z axis of the
target is unlocked. More effects are possible an can be
combined.
This (biggish) commit generalises the rotation modes functionality added for Bones, allowing Objects to use the various Euler Rotation orders, Axis-Angle, and Quaternion rotation representations.
I've also cleaned up the nomenclature of the rotation-related settings so that the naming styles are more consistent with each other. Unfortunately, this will break all files involving object or bone rotation animation made in 2.5 versions (2.4x will still get correctly converted).
General Notes:
* By default, Objects still default to using Eulers, while Bones will use Quaternions by default still.
* I've fixed all areas that I'm currently aware of to work with these changes. However, there are probably a few places where I've missed a few changes (i.e. auto-keyframing will need attention later).
* Removed the old "IPO-Keys" stuff from Transform code. I'm unlikely to restore this in the near future, and trying to fix that to include support for this commit would have been too much work.
