add panel for MNE in new GUI

[jasmainak]

This is something to consider once we have the new GUI in place. You can potentially have a panel for loading in STC files and allowing the user to click on vertices so it shows the dipole waveform on the HNN waveform. This is totally doable and was part of the original HNN grant/vision

[jasmainak]

alright folks, here is a very quick minimal demo:

https://gist.github.com/jasmainak/865c56aae4e172d40b3336ae7e091cc1

screenshot:

thanks @alexrockhill for the help

give it a try. It should work on hnn-core master with the 3D viz dependencies of MNE: pyvista, pyvistaqt, ipyvtklink, and ipympl.

NOTE: the brain plot is interactive! You can rotate it :)

[jasmainak]

You can't click on vertices yet but I'm sure it's doable :)

[jasmainak]

picking also works, yayyy!

[rythorpe]

You can't click on vertices yet but I'm sure it's doable :)

Clicking on vertices works for me! This is super cool.