Fixed crash when importing a rigifiable armature.

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4758 96b784f8-4ae3-dd11-aff7-0030488c597c
added: exporter takes armature parent in account of animation handling.

only one armature source will can be taken at the moment, and will taken in the following "priority" order:
1. armature parent will be taken if exist.
2. first available armature modifier will be taken if exist.

open question: what is best practice, in case of existence of multiple armature sources?
(armature parent and one or more armature modifier)
can that case happen (very often) in real world mesh modeling?

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4759 96b784f8-4ae3-dd11-aff7-0030488c597c
Fix [#36268] FBX exporter precision min is too big

Using a bit more flexible way to handle those values (range now from 10^-18 (20) to 10^2 (0) frames). Not sure we shouldn't rather get rid of such "magic" value and let user set frame threshold directly, though!

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4760 96b784f8-4ae3-dd11-aff7-0030488c597c
Eeek, revert some changes that should not have been committed!

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4761 96b784f8-4ae3-dd11-aff7-0030488c597c