Added unittest and 1 system tests. Includes 1 bugfix to resolving a circular import and 1 bugfix where dms wasn't creating the topology correctly when the water was specified in different chains
Bugfix: dms.positions should be a Quantity(list(Vec3)), not a list(Quantity(Vec3))
typo: extra s
same fix about list(quantity) vs quantity(list) for unitcell dimensions
Merge pull request #156 from rmcgibbo/dmstests

dmstests