922 - fill starts off as right color before transition

Massive refactor of animator as well as some edge case fixing
Also a precommit for #918

Close #922.
cleanup code
Merge pull request #923 from palantir/922-fillStackedBarAnimator

922 - fill starts off as right color before transition
Change directory structure to be more sensible
Update reference.ts, etc
Update built files.
Merge pull request #939 from palantir/directory-structure

Change directory structure to be more sensible
Merge branch 'develop' into api-breaking-changes

Conflicts:
	plottable-dev.d.ts
	plottable.d.ts
	plottable.js
	src/reference.ts