Merge pull request #4148 from RosettaCommons/JWLabonte/PDB_IO/HETATM_records
PDB IO: Correcting how HETATM records are decided
This merge corrects how Rosetta decides between writing a PDB ATOM record and writing a HETATM record.
Historically, Rosetta saved LIGAND ResidueTypes with HETATM and POLYMER ResidueTypes with ATM. This was in conflict with how the records are defined by the PDB, which is that only canonical AAs and NAs get ATOM records; all other types of residues should receive HETATM.
See issue #3509 for further details/discussion.
All unit tests pass.
98 integration tests give expected changes with a multiplicity of .pdb output lines changing from ATOM to HETATM.