[Bf-python] extrapolation types

[Willian Padovani Germano]

> Here's another prob for ya!

Yes, I remember this problem, got into it when I added insertMeshKey, etc in
NMesh.  Was in a hurry at that time, guess it was right before 2.28's
release.

For meshkeys I had to copy one function from Blender and comment a part of
it so I could use only what I wanted.  This is always an alternative, though
obviously not that good (duplicating code).  But surely the best is to talk
to Ton first about it.  If he worked on that, he may have something to say
that we should consider.

--
Willian, wgermano at ig.com.br