Split getBar/selectBar API
getBar tests
Pruning irrelevant selectBar tests
getBar -> getBars
Merge branch 'develop' into getBar
getBars always returns a selection
Destroying selectBar
d3.select()
bars.empty()
Change d3.d.ts to pull request version
Changing select_bars so that click/drag do stuff
Merge branch 'develop' into getBar
Merge branch 'develop' into getBar
hoverInteraction hovers/dehovers if getBars is not empty
Merge branch 'develop' into getBar

Conflicts:
	plottable.d.ts
	plottable.js
	src/components/plots/abstractBarPlot.ts
Merge pull request #1318 from palantir/getBar

[BarPlot] - getBars() API