Add detect_impulses()

[ymtoo]

This function is useful to detect impulses such as snapping shrimp noise.

[mchitre]

What is the advantage of this over find_peaks?

[ymtoo]

detect_impulses first transforms an input signal into envelope and then detects peaks from the signal envelope using find_peaks with minimum peak height defined by multiple of median absolute deviation (robust standard deviation) and minimum time difference between neighbouring impulses in seconds.

It's a specific function of find_peaks with a preprocessing procedure (to get the signal envelope).

[mchitre]

OK, merging