Add support for FFT integration

[dbrll]

Could you add the support of FFT integration, aka, averaging x number of FFTs?

This has numerous uses, including better power measurements and smaller FFT files (used in radar and radio-astronomy applications).

Thanks!

[ha7ilm]

Please check this pull request:

#19

Does this help you?

[dbrll]

Sorry for the late answer. From what I see, and unless I'm wrong, logaveragepower_cf would work but seems to average the whole FFT power, whereas I would need an average of each FFT bin from several FFTs. This is required for spectral analysis of low power signals.