[ENH, WIP] Add localization for microgrids

[alexrockhill]

This implements a minimal working example with several to dos for localizing a grid based on a surgical image by moving around spheres representing recording contacts in 3D.

cc @mmagnuski in case this is useful for you as well or if you want to help review/request features.

tumor_loc.webm

[alexrockhill]

Here's a version with lots of added features:

new_grid_loc.webm

[alexrockhill]

TO DO:

• Implement show/hide surface for every added surface
• Write tests
• Optimize camera location given intraoperative photo (grid search and then fine-tune?)
• Add example data to misc data?
• Write example
• Grid to UV mapping?
• Shrink inner skull surface around pial surface to allow sulcal penetration
• Pull contacts in direction of neighbor if normal distance to neighbor exceeded (like cloth physics)

[alexrockhill]

@larsoner if you have a second do you know if this Qt window closing failure is solved in mne-python and if there's something to copy over?