add one_to_many support to collapseObservationsByMetadata
added collapseSamplesByMetadata
performance tweak, using numpy vector ops
updated forloops to for-from style recommended by cython instead of relying on range()
Merge pull request #92 from wasade/sparsemat_cython_tweaks

updated forloops to for-from style recommended by cython instead of rely...
addressing Jai's comments
More docstring updates
added ChangeLog mention
Merge pull request #91 from wasade/one_many_bin

One many bin
fix to csmat bug not handling numpy arrays
Merge pull request #96 from wasade/to_csmat_bug

fix to csmat bug not handling numpy arrays
to_sparsemat now handles numpy matrices
to_sparsedict now handles numpy matrices
Merge pull request #98 from wasade/to_sparsedict_bug

to_sparsedict now handles numpy matrices
Merge pull request #97 from wasade/to_sparsemat_bug

to_sparsemat now handles numpy matrices