Fix [#37029] FBX Export does not work if Mesh has no Material.

This situation was simply not handled in existing code. Also removed last use of tessellation (my bad, should have checked this before), and enhanced/cleaned up a bit mat/tex handling.

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4791 96b784f8-4ae3-dd11-aff7-0030488c597c
Added a patch by Markku Myllymaki, for animated textures using numbered images.

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/trunk/py/scripts/addons@4792 96b784f8-4ae3-dd11-aff7-0030488c597c