Blender Git Loki

Fix for CrazySpace correction. (Special request of our Argentinan bird
movie friends :)

There were two issues with it, which both have been tackled as follows:

- the correction transformations (quaternions) were calculated per face,
and then averaged over the vertices. This gave annoying inaccuracies,
especially when the geometry is irregular.
The new code first calculates two tangent vectors in a vertex, based on
the associated edges it has in a face. These tangents then are used to
define the transform. Tangents are 20% of the length of an edge now.

- When a SubSurf modifier was in the chain, the deformation caused by the
subsurf was also included in CrazySpace correction, giving even larger
errors.
New code temporally disables Subsurf, recalculates vertices, and then
does the crazy tricks. :)

All in all, quite well working!