[initial commit] StackedBarPlots are now a thing.
They descend newStylePlot, which implements the new dataset api.
clustered bars
Remove vestigial code
- Stacked extent management handled by _updateAllProjectors
- Add the baseDrawer class
added legend to quicktest (buggy)
NewStyleBarPlot is now a thing
Merge branch 'stacked-bars-simpler' into clustered-bars
Merge branch 'master' into clustered-bars
remove stacked-bars from this branch
Clean up handling of updateYDomainer, updateXDomainer
clustered bars descend from newstyleplots
Various improvments:
NewStylePlot - interface DatasetDrawerKey so key is easy to obtain and we have just 1 object encapsulating necessary info
StackedBarPlot - now use a keysInStackedOrder array to maintain stacking order
Plot - projectors now store attribute as well as scale/accessor for convenience later
remove shift button
Move the KeysInOrder down to NewStylePlot
Merge branch 'stacked-bars-simpler' into clustered-bars

Conflicts:
	plottable.js
	src/components/plots/stackedBarPlot.ts
	src/core/newStylePlot.ts
fix tests
fix tslint
fix travis error
[refactor] NewStylePlots don't take dataset as constructor argument
[refacotr] Add helper functions for getting drawers and datasets in order
Merge branch 'stacked-bars-simpler' into clustered-bars

Conflicts:
	plottable.d.ts
	plottable.js
	src/components/plots/stackedBarPlot.ts