Lengths
Minor change I noticed looking at the diff
Merge branch 'master' into file-object-length
qMerge branch 'master' of github.com:rmcgibbo/mdtraj into file-object-length
qMerge branch 'file-object-length' of github.com:rmcgibbo/mdtraj into file-object-length
Moved the load_xxx methods out of trajectory.py, new registry
py3 fixes
Fix typos from looking at the diff
Update docs for open()
Merge pull request #253 from rmcgibbo/file-object-length

Add __len__ to each of the file objects, add md.open() to API