rffft wav support

[MartinHerren]

This PR adds native WAV file support to rffft. It works as well with int16, float32 and other WAV files as well as RF64 (WAV64). As it is based on PR #52 it also adds automatic options extraction through the -P parameter from the filename of WAV files exported from SatDump and SDR Console.

This PR is based on #52 (and thus also #48) so should not be merged before they are merged.