Enable QTAIM rendering engine when beginning analysis.

Suggestion from Henry Rzepa. Still might require turning off
ball-and-stick, stick, or other display types, but I don't think
this should be done automatically.

Change-Id: I3162a825ca053003c8a348a6eae33236532dde43
Merge topic 'ENH_turn-on-QTAIM-engine' into master

02396b4b Enable QTAIM rendering engine when beginning analysis.