support for CoSMoMVPA

CoSMoMVPA is a toolbox in matlab inspired by PyMVPA.

This PR provides
- dataset input/output support
- neighborhood (a.k.a. query engine) input support
- unit tests
Two questions?
1) doctests have 3 '>' (greater-than) characters, not 2, as far as I know. Thus, doctests should not choke in this, should it?
2) the data used here is only really useful for unit testing... is it a proper place for mvpa2/data/cosmovmpa then?