BUGFIX: sanitize input parameters
Suppress Numpy config related warning if not in debug mode. Guess cblas.h location on OS X too.
Add simulations_backends variable and doc.
TRAVIS-CI: Install BLAS.
BUGFIX: fix impL1() for polyphase filters
TEST: add test for polyphase filter
Merge branch 'master' of https://github.com/ggventurini/python-deltasigma into tests