* Multithread parts of multires and subsurf. Only loops working on
face grid data and do no memory allocation have been multithreaded,
others would be more complicated.
* Force some CCGSubsurf functions to be inlined, gives a small overall
speedup in subsurf code.
* Fix sculpting not working correct with transformed objects.
* Fix a few cases of "spikes" on lower level multires levels. There's
still cases where it happens, usually on boundary cornders. The
problem is that in such cases the limit surfaces can be very different
from the low res surface, so the tangent space is very different too..
* Fix crash deleting multires higher levels with level set to 0.
* Fix crashes that happened sometimes when adding faces in editmode.
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