Clean up handling of updateYDomainer, updateXDomainer
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