Blender Git Loki

Fix T94144: Duplicate edges in dual mesh node

The duplicated edges were caused by 'oversubdivided' edges, i.e. edges
where some of the vertices on them are only connected to two polygons.
The fix finds these vertices and 'dissolves' them so that only one edge
is created.

For most 'normal' meshes this shouldn't occurr, or only very little, so
the performance impact of this change should be neglegible. In practice
this is also avoidable by triangulating the mesh first.

Differential Revision: https://developer.blender.org/D13445