moving keyboard events into a mixin

[bakesteve]

• [x] Row Click
• [x] Cell Click
• [x] Key events
• [x] Cell marked as seleted
• [ ] frozen columns
• [ ] scroll past visible area

[bakesteve]

done this using flux a few thoughts so far:

• one way data flow is clean
• lots of boilerplate, bit of a pain. And the "constants" are magic strings. I HATE magic strings.. maybe look at https://github.com/spoike/reflux
• stores being singleton make a lot of sense, but not for base / reusable components. maybe give the store a grid id?
• injecting in SelectableCell onto the col.renderer feels either neat or incredibly hacky..

[bakesteve]

been cherry picked / re-done