add the duration over which the psd is calculated to the template length for psd ringing instead of 32s

- make sure k argument is not manipulated with integer arithmetic
- use numpy.sqrt() instead of ()**.5 because I think I decided the former
  was faster at some point
- pre-compute 1./2. (in case the Python interpreter isn't smart enough to do
  this optimization)

- command line option wasn't doing anything.

- this is a separate patch so that it can be reverted easily later when
  we're comfortable the new-and-improved capabilities of the muxer won't
  break anything

- allow not just exactly 1 FrVect per channel per frame
- construct the FrVects directly from the GstBuffer data, removing an
  intermediate malloc() and memcpy()
- note:  apparently only the demuxer element can read the files this thing
  now generates, so it is left as an exercise to the application to provide
  data streams that don't exercise these new features unless it is OK to do
  so.  the previous version of the code would refuse to process streams
  that exercise these new features, so any application that worked at all,
  before, should not trigger problems now.
- add an EOS log message while we're at it

inspiral.py: remove subdir option from the T050017 filename function and move it to a separate function

gstlal_ll_inspiral_create_prior_diststats: a program for adding prior distributions to the online analysis

gstlal-inspiral/bin/gstlal_ll_inspiral_pipe: Updated doxygen
documentation and changed --channel --> --channel-name to match the
convention set in datasource.py.

gstlal_ll_inspiral_pipe, and inspiral.py. PR 2018.
Major changes include:
gstlal_inspiral: Now takes reference likelihood files that detection statistics
can be read from every snapshot interval so that jobs with software injections
rank events the same way as jobs without software injections.
--reference-likelihood-file and --likelihood-file are mutually exclusive
options.
inspiral.py: Changes mainly to account for new reference likelihood file option
gstlal_ll_inspiral_pipe: Modified to allow adding parallel gstlal_inspiral jobs
for software injections