added comment to gelsd
removed defunct function from Matrix classes
added closest_point to ParticleTree
Merge branch 'master' of github.com:otherlab/core
Merge branch 'master' of github.com:otherlab/core
Merge branch 'master' of github.com:otherlab/core
Merge branch 'master' of github.com:otherlab/core
exposed stuff to python