Added save() for legacy HDF
Minor docstring update for compat
Added pre-loading of top in multi-traj loading.
Added comment of kwarg processing.
Merge pull request #190 from kyleabeauchamp/load_speedup

Load speedup
Use iteritems from six for py3k
Merge pull request #187 from kyleabeauchamp/save_legacy_hdf

Added save() for legacy HDF