We have been kind of inconsistent about molecularhierarchy-related
helper methods, for example molecular_hierarchy_get_by_type. Some of
the methods have a molecular_hierarchy_ prefix and some not. I propose
(as was Ben's preference when this was discussed before) to remove the
prefix from the methods which have it:
molecular_hierarchy_get_by_type becomes get_by_type
and
molecular_hiearchy_get_residue becomes get_residue