Enhancements and updates for SfN2015

[bcipolli]

Too many to list. Here's the direction I've gone:

brain.js

• takes a manifest_url (which can contain filenames, colors, values) and, optionally, a data_url (same stuff but no filenames). This allows repainting the brain without having to specify filenames.
• values and colors can now be a dictionary, with value_key specifying which key to select / display. This allows a single JSON to be used for multiple brains.

hemi-plotter.js - A new module that implements higher-level interactions with surfaces:

• single mode: when JSON has a single value, creates a single surface and paints data on there.
• multi mode: when JSON has multiple values per ROI, creates multiple surfaces, one for each value.
• master/slave mode: when click from one surface leads to a data change on a second surface. See http://cseweb.ucsd.edu/~bcipolli/docs/posters/SfN2015/brain/similarity-slave.html for an example.

The code isn't the prettiest, but I'd like to merge this and tag it for SfN2015, then keep working from what's here to improve.

[binarybottle]

Fantastic work, Ben! If I hold the shift key, I am able to mouse over the different regions and see the tandem panels respond with appropriate anatomical label on top. Good show! How was the reaction at SfN?

[bcipolli]

All three people who saw it liked it LOL https://twitter.com/mrquickowl/status/656526146616586241 https://twitter.com/mrquickowl/status/656563259936477184 https://twitter.com/EvaDundas/status/656565974796144640

[binarybottle]

Ha! I'm sorry you weren't booked for a dynamic poster, but it is more important that it live its digital life in perpetuity online!