Add back in fuller QM capabilities - molecular orbitals

Added back in fuller functionality for calculating molecular orbitals
and electron density. Keeping the convenience functions for now to
quickly calculate the HOMO/LUMO.

Change-Id: Ic88ab077c864828e3f06aeb06f0f3f2f169464e4
Set cancel to NULL, improve logic for QM or not

Responding to review comments, hide cancel until it is actually enabled
and store the basis set as a variant value so the extension can tell if
the current molecule has associated QM data or not.

Change-Id: I38df1fa9ab316d6ed58fa7e57968ad07dd25bd50
Merge topic 'quantum-dialog' into master

b791201b Set cancel to NULL, improve logic for QM or not
55fbebec Add back in fuller QM capabilities - molecular orbitals