ENH: speed up filtering
WIP: refactoring
WIP: Remove duplicated code
WIP: more refacoring to remove duplication
BUG: off by one bug
BUG: 0 vs 1 (aka sample vs observations, thanks @wasade)
MAINT: numpy namespace
TST: Add tests
TST: add tests and remove old ones.
BUG: turns out ids are numpy arrays with dtype=object
TST: unused imports
TST: we're actually doing an in-place installation.

I.e. same fix as https://github.com/biocore/scikit-bio/commit/fdc4e6a9e3c306ccf3db7b1b22a099e86c1c4010
TST: matplotlib isn't actually used
ENH: accept iterables too
TST: add cython
TST:  remove unnecessary apt-gets
DOC: add docstring to filter
MAINT: remove duplicated imports
BUG: there were two test methods with the same name
BUG: Another name clash (a class was overiding other ones)