Blender Git Loki

Fix minor Mesh -> BMesh conversion issues

- Vertex only meshes never restored their selection history.
- Select history was cleared on the source instead of the target.

Simple Optimizations:
- Avoid O(n^2) linked list looping that checked the entire list before
adding elements (NULL values in the source array to prevent dupes).
- Re-use vert & edge lookup tables instead of allocating new ones.