- Provide a function in the BaseSearchClass to read in the ephemeris
  files
- Some clean up of docstrings

Since each SFT is generated in a for loop, the process can be quite
slow. This allows the user with `pathos` multiprocessing installed to
leverage `-N` cores (set by command line arg) to speed the process up
Setting N=1 or if pathos is not installed, reverts to the usual
behaviour.

- Adds function to use XLALCWSignalCoveringBand
- Fixes issues in injection_helper_function, both are checked to agree

 -try-except wrapper for subprocess.check_output()
 -use this for MFDv5 call (properly terminate at error!)
 -and for other small utility calls
 -use unique variable names for cl strings too

- Add peak detection utilities
- Move generate_loudest
- Add SSBprec pass through to MCMC searches
- Fix convergence stat (missing sqrt)
- Minor fixes to plot_walkers (put detection statistic behind walkers)

- Adds latex prior table writer (not found to be useful)
- Add special case of 0 to texify_float
- Expose texify_float in core
- Fix confusing argument order in GridSearch

1) Adds 'add_noise' option (defaults to true)
2) Better checking of Writer for if all glitch parameters have the same
length (avoid strange errors)
3) Fixes issue in which the tqdm ignore command was itself ignored

Transforms the single pyfstat.py into a python module splitting the
relevant code into separate sub-files in pyfstat. This should result in
improved readability.