When the tagger loses focus, close the candidates box.
Once we've added a tag, clear the tagger's entry box.
Block focus-shifting when using tab-to-autocomplete.
Don't show the tagger suggestion box for nonprintable keycodes.

It used to be the case that pressing e.g. modifier keys would cause the
suggestion box to show up.  That gets confusing.
When clicking a tag suggestion, prevent event propagation.

If we don't do this, then we'll go to #, which plays quite badly with
Ember's history tracking and manipulation code.
New colors.

Parameters: Triadic scheme with #520063 (NU purple) is the base color.
The accent colors are 60 degrees offset from the base.
Don't sort every time rows change.

This resulted in one sort per row added (!), which is way more work than
necessary.

rebuildIndices is a pretty funny place to put this, but it works for
now.  I'll look for a more appropriate hook later.
Correct sorting operation.
Return a greater amount of test data from Cases mock.

This helps me figure out how the grid behaves in more realistic
situations.