Molsystem

* Added control to from_RDKMol and from_OBMol to allow selectively updating
the atoms, coordinates, and bonds

* Molecules created from line notation are created in an random orientation. This
enhancement rotates them to the standard orientation, which will look nice for
small, symmetric molecules.

* There was an indexing bug translating bonds back from RDKit to SEAMM. The famous
0/1 problem!

* Added gradient on atoms as a separate table alongside atoms, so they take no space
unless actually used.

* the Crystallographic Open Database CIF files seems to use upper case X, Y, Z in
explicit symmetry operators. These need to be lowercased in the code.

* Fixed issue 72, where symmetry was not correctly handled for trigonal and
hexagonal cells where atoms had coordinates of 1/3 or 2/3.