added an average FFT example for HDF5 output
actually the length of the FFT is only slice_size long!
fixed the center frequency and span issue.  reproduces tone frequency
for RSA data.
Removing unnecessary debug print statement. Bumping version to 1.10.13 for this and HDF5 writer fixes by Jared.
Merge branch 'develop' of github.com:project8/katydid into develop