Blender Git Loki

Optimize meta-ball basis check.

`BKE_mball_is_basis_for()` was processing whole name, when we can
actually rule out most of cases by just checking third char of the ID
names first, which is much, much cheaper.

Even though MBalls are not much used nowadays, that's a nice
optimization when this is called over a whole Main database full of
meta-balls objects...