Added the ability to interpolate in the frequency domain to
Trace.resample(). Allows resampling with an arbitrary sampling_rate. Fixes
issue #857.
Use scipy.fftpack.rfft in place of np.fft.fft, raise exception if window
has th wrong shape, clean up
Merge pull request #859 from kaeufl/releases

Added the ability to interpolate in the frequency domain to Trace.resample(). Should fix issue #857