corrected arguments to AASiteType in pele/angleaxis/aatopology.py
saved symmetry operations as angle-axis rotations as well as matrices in pele/angleaxis/rigidbody.py
added MolecularCluster cluster class and associated minperdist classes/routines
minor reformatting
added simple water cluster test
modified the testing routines
added Molecule class, overloaded various AtomicCluster methods
added water cluster example
Merge pull request #60 from jdf43/molecular_cluster

Molecular cluster