Rigify: removed "from rigfy import X" statements where possible.

This makes it much easier for e.g. someone to branch Rigify for
custom purposes, since there won't be weird name conflicts.

Also changed from using __import__() for dynamic imports to using
importlib.import_module().  This simplifies the code and should
be more robust.

Finally, misc pep8 cleanups.


git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4282 96b784f8-4ae3-dd11-aff7-0030488c597c
markers may have duplicate labels; thanx to Jens Meisner for the bug report


git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4283 96b784f8-4ae3-dd11-aff7-0030488c597c
Rigify: updated naming schemes for control bones.

This required changes to both the default human metarig and some of
the rig types.  This updates the naming scheme to match new
best-practices, as per the CGCookie Flexrig.


git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4284 96b784f8-4ae3-dd11-aff7-0030488c597c
Rigify: changed rig type API.  Disabled delta rig type.

I have updated the rig type API to be a bit clearer based on my
interactions with Kfir from PitchiPoy.

I've also disabled the "delta" rig type, as it is very obscure and
mostly just confuses people.


git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4285 96b784f8-4ae3-dd11-aff7-0030488c597c