Blender Git Loki

Fix for bug #4912: Interface freeze with scaling object with subsurf + array
modifier.

The bug was caused by an endless loop in the Array modifier's calc_mapping
function. The loop worked under the assumption that there could not be sets
of vertices such that (for example) vertex A merges with vertex B and vertex
B merges with vertex A. As it turns out, this situation is possible, so the
loop got stuck going from A to B to A to B ad infinitum.

This commit fixes the problem by limiting the number of loop iterations with
the copy number for which the mapping is being calculated. This should also
give more correct results in general.