Closes #7

 -replaces boolean 'transient' flag
 -window type [none,rect,exp]
  for both injections and searches
 -t0, tau bands for gridsearch,
  single-point use (e.g. MCMC) should be unchanged

Previously, a check was done to ensure that all initial positions of the
walkers would yield a non -np.inf prior. This extends this to also check
the likelihood evaluations. The method is also simplified partially

Partially resolves issues in #6

- Adds labels of each stage along the top
- Fixes bug when re-running
- Improves column title of run_setup table

Previously, we used the emcee.PTSampler, but this has been removed from
the master branch of emcee (see discussion here
https://github.com/dfm/emcee/issues/236) and a fork, ptemcee has been
developed. Testing shows this is equivalent (after some changes in the
interface) and perhaps better as it contains the adaptive temperature
ladders developed by Will Vousden (the maintainer of ptemcee)

 This removes the convergence testing ideas previously implemented
 (currently juts commented, but later to be fully removed). These are
clearly not useful without further study, which in itself would be a
better time to develop an implementation.

- Remove minStartTime, maxStartTime and outdir as default arguments
- Adds notes ot documentation on which arguments are optional
- Change log-level on some command line calls that dont' matter
- Reorganise the tests performed after loading the data
- If minStartTime and maxStartTime are None, set them using
  SFT_timestamps
- Remove default labels from plot_twoF_cumulative
- If add_pfs is called, call generate_loudest automatically
- Save min/maxStartTime in pickle and load if required

Fixes #4 .

The variable name was misleading and hence renamed

This adds a new method `setup_initialisation` which can be called to run
the initialisation step. Splitting it out from the main functionality
should make it easier for new users.

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

- Remove arbitrary dpi choices
- Set the xlimits to remove white space before and after

- Adds autocorrelation attempt (using PR 223 to emcee)

- Cleans up convergence messages
- Adds autocorrelation calculation
- Provide acccess to `c` parameter
- Improve overall documentation of run()

Note - the calculation of V is still incorrect, this just changes the
user interface