Speedup math operations

[fungs]

The code is currently slow, we can do much better using

• removing assertions in non-debug mode
• scaling data at the beginning to avoid likelihood calculations
• speeding up vector arithmetics with more advanced python packages/methods
• avoiding the time for parsing the data over and over again

[fungs]

Considerations:

• numexpr, theano or numba for faster math
• Cython
• numpy.ascontiguousarray, numpy.vdot, numpy.memmap