ENH: Optimize Cython code. Use scipy blas function pointers.
DOC: Mention arma speed-ups in release notes
COMPAT: Try to use Python 2/3 function declaration.
TST: Suppress not assert on possible warning.
Merge pull request #1524 from jseabold/arma-speedup-scipy

ENH: Optimize Cython code. Use scipy blas function pointers.