Add text parsing to BOND_TYPE lines
Instead of SDF-based numerical values, you can now use text
designations (like ARO or DELOCALIZED) to specify bond types
in params files.
Database files have been updated to use the new scheme, but
molfile_to_params.py will still output the old numeric values.
No substantive test changes expected.
(Standard numeric variablilty with ligand_dock_script encountered.)