Merge pull request #1367 from RosettaCommons/rhiju/magnesium_in_stepwise
Code updates needed for modeling RNA residues around magnesium ions for ERRASER and stepwise modeling. Includes code for optimizing water locations and orientations around Mg(2+) during stepwise.
No tests change, except for floating point issues & minor output changes to mg_modeler & number_of_residue_types, which are expected.