BUG: Make selections more permanent, linked to object

The bar charts selection was quite fragile, being attached to objects
that are deleted and recreated on any given update to the bar object.
This adds the selection directly to the selection array, and instead
of changing the color overpaints a bar blending with the original
colors, making it easier to see multiple different colored bars that
are selected.

Change-Id: I84b1128c26af5743af9868adc72e0da038ea775c
STYLE: Some basic style fixes

Missing braces, whitespace.

Change-Id: I4cf767816b4fc68211bc58fecc34d387f2d4a204
Removed sorts as the inputs were already sorted

Change-Id: I7810ef3e0a96ddce33ef17bff22247a1834530db
Added a test to exercise bar graph selection

Change-Id: Id90e98ae40559ef6076e9b9323824f47a08395f1
Merge topic 'bar-chart-selection' into master

4940fde0 Added a test to exercise bar graph selection
4666a708 Removed sorts as the inputs were already sorted
3c35743b STYLE: Some basic style fixes
45185724 BUG: Make selections more permanent, linked to object