Fancier brain plots using ipyvolume

[jeremymanning]

Let's add ipyvolume to the requirements. We can then add a plot_volume function to Brain objects and Nifti objects. For example:

import ipyvolume as ipv
gray = se.load('gray')
ipv.quickvolshow(gray.get_data(), lighting=True)

Other ideas:

• It looks like, by default the volume rendering is flipped 90 degrees...we'll need to figure out how to rotate the camera to correct for that
• we could use this volume rendering to make animations. i think they'd loop pretty neat

[jeremymanning]

Let’s punt this to a future release

[jeremymanning]

It looks like MNE python might be working on this too: https://github.com/mne-tools/mne-python/wiki/Engineer-position-in-3D-scientific-visualization-in-Python