Merge pull request #4378 from RosettaCommons/roccomoretti/more_residue_selector_switch
Convert a bunch of XML object to use ResidueSelectors internally.
Another spinoff of PR#2466, aiming at removing the pose dependence at parse time.
There's a number of objects which use pose in parse_my_tags() which can (and likely should) be converted to using /ResidueIndexDescriptors. (Note that I haven't changed the XML interface, just implemented the internals with ResidueSelectors/ResidueIndexDescriptors.)