Add extremestats

[fhagemann]

This takes a waveform or an array and determines the extrema (min, max) and their time values / indices (tmin, tmax).

Example:

using LegendDSP
using RadiationDetectorSignals
using Unitful

wf = RDWaveform((0:1:360)u"ns", sind.(0:360))
extremestats(wf)

(min = -1.0, max = 1.0, tmin = 270 ns, tmax = 90 ns)

Just like signalstats and tailstats, you can pass start and stop, but it is not required (see tests).

[theHenks]

Thanks!

[fhagemann]

@MayaMenzel