[enhancement] symmetry exploitation

[shaunlebron]

Since the symmetry implementation was only meant for a cubemap, there must be a generic way to define how a globe handles symmetry.

I think lenses should have an additional symmetry property, rsym, for rotation symmetry.

The globe scripts will probably need some callback functions for handling symmetry. I'm not sure yet.

[shaunlebron]

hard to make this generic enough to