Merge pull request #3280 from RosettaCommons/roccomoretti/PDB_loading_segfaults
Fix segfaults occurring in PDB loading scientific test
Two classes of segfaults were happening in the PDB loading tests
* When building a Foldtree, we were checking if a residue was in an empty foldtree. This lead to a crash instead of just saying it wasn't.
* Some PDB components have hydrogens with two bonds to them. This violates some assumptions Rosetta has about hydrogens and only belonging to a single atom. Catch this earlier.
There's four PDBs which now are failures which used to be "successes" - turns out they were suffering from the same issues which were causing segfaults, but weren't actually triggering a segfault for some reason.