Merge pull request #1771 from RosettaCommons/roccomoretti/specificer_patch
Add a "HasAtom" patch selector.
The patch interoperability logic can get a little cleaner if we can test for the presence/absence of particular atoms on which we're going to work. This merge adds such an HAS_ATOM patch selector, so you can test if the ResidueType you're attempting to remove the H atom from really does have that atom.