Blender Git Loki

Isomap Unwrapper
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* Fix, pass squares of distances to eigen solver
* Use a heap instead of a stack to get the next vertex to iterate
through in Dijkstra graph search algorithm. This is needed because we
may follow a non-optimal path and not get the nearest path between
vertices. This introduces the O(n*log(n)) performance (was more like
simply O(n) till now, but unfortunately, it was incorrect).