Moved PSD creation methods to new gwpy.signal.fft module
This PR moves a bunch of modules out of the gwpy.frequencyseries sub-package, and into a new sub-package of gwpy.signal, which should make them a bit more obvious to the user.
The new gwpy.signal.fft module consists of three modules:
-
gwpy.signal.fft.scipy- API to thescipy.signalPSD-generation routines -
gwpy.signal.fft.lal- API to thelal.REALXAverageSpectrumXXXroutines -
gwpy.signal.fft.registry- utilities to expose routines from the above modules toTimeSeriesinstance methods via keyword argument specification.
I also cleaned up the docstrings for methods requiring the new gwpy.signal.fft registered methods, and added documentation of gwpy.signal.fft so that this should all be more transparent.