gstlal_inspiral_pipe: Remove FIXME that was addressed by commit 416627b7

- in the FIR-whitener code path

- only add a pre-whitener reblock element in the non-FIR whitener code path

- check that psd_fft_length is an integer

- confirm the channel list matches the instruments in the time slide vectors
- confirm the reference PSDs, if given, match the instruments in the time slides

- in gstlal_inspiral and gstlal_fake_frames automatically enable PSD tracking when a reference PSD is not given instead of reporting it as an error
- in mkwhitened_multirate_src() require track_psd to be set if psd is None
- flatten initialization of whitener's psd-mode property

gstlal_inspiral_pipe: Set svd job priority to 99. Should make all svd jobs submitted before insiral jobs

gstlal_harmonic_sum_psd->gstlal_harmonic_mean_psd: changed harmonic sum to harmonic mean, fixed minor typos

gstlal_inspiral_pipe: Inspiral jobs will no longer wait for all of the svd jobs to finish before starting

muxcollectpads.c: fixed typo in chain causing bpf (bytes per frame) to be set incorrectly in gst_audio_buffer_clip

- implement whitener initialization from calling code supplied PSD
- had been disabled since introduction of FIR-based whitening while we
  became comfortable with it, but no longer any reason to leave it disabled

- set to 1/4 psd_fft_length if not set by calling code unless FIR_WHITENER is turned on, in which case set it to 0