improvements to iterative deconvolution
improvements to iterative deconvolution

* allow arbitrary source time windows
* default source time window does not use a taper
* fix zeros at end of receiver functions
* no wrap-around in receiver function due to time shift
* therefore no no need to mute the beginning of trace
* turn muting off by default, new kwarg to control this behaviour
* return rms list
* return number of iterations as list of integers
* minimize number of ffts

trichter/rf