Merge pull request #2805 from RosettaCommons/jadolfbr/improve_glycan_error_handling
Improve Glycan Error Handling
This PR fixes map access in GlycanTreeSet so that we actually check if the residues are there before accessing them. This allows us to cleanly exit with helpful error messages.
This also adds more helpful XSD text for GlycanTreeRelax and GlycanRelax use of the Residue Selector. We also now check to make sure we only have glycans selected from the ResidueSelector in GlycanTreeRelax - instead of cryptic crashes.
Cosmetic integration changes expected in all tests that load glycan poses.