added 'fastsearchsorted' to methods excluded from testing in `np.matrixlib`, which was causing a testing error
Implementation now switches to linear search for smaller haystack arrays.
Main thing slowing down implementation on floating point types seems to be
the rich comparison properly handling NANs, an implementation dealing with
this differently (and showing a 20% speed up for inputs with no NANs) is
commented out in `binsearch.c.src`. Not sure the performance improvement
warrants the ugliness of the code!