Blender Git Loki

improve editmode triangulation by re-using the loop array when
possiblem, this has to guess when the size is too big so as to re-
well.

If this isnt done, then the number of faces is used to allocate the
initial array to at least avoid many small allocs.

added BLI_array_reserve() to reserve elements and avoid reallocing many
small arrays when the loop starts.