Multires interpolation is now nearly perfect, but has some
issues on faces whose angle to each other isn't relatively
shallow (probably need to use some sort of fast spatial structure
to more accurately project multires points).
It also doesn't work super well with bevel (mostly due to a
flipped normals bug in bevel I need to get around to fixing).
And, for some reason extrude tends to explode the multires
geometry (it should just be copying it).
Since edge cut doesn't do anything yet with face interpolation,
cuts that arn't exactly centered will move the underlying multires
geometry around a bit..
f4a2008441