Blender Git Loki

Add a bmesh_core_test, a start at testing bmesh functionality.

Needed to make the blender link libraries a global property
now that tests are parallel to source directory.
Current sort order for blender link libraries doesn't work
for tests that start with few defined symbols. Doubling the
lib list works, but a TODO to find a better way (probably
using CMake's own mechanism for tracking dependencies).