Adds documentation for implemented samplers

See merge request Monash/tupak!183

Add function to plot data with draws from the posterior and max like

See merge request Monash/tupak!176

Resolve "units in latex labels"

Closes #107

See merge request Monash/tupak!184

Resolve "add neutron star merger to examples"

See merge request Monash/tupak!187

This reverts commit 46b9e61a.

Note - also forces all `__init__` calls in `prior.py` to use key word
arguments to ease changes in the future.

* Adds a CLI arguments `sampler-help` which prints the docstring for the
  given sampler
* Documents each Sampler class with details of the commonly-used kwargs
  and information on where the kwargs are passed (except for pymc3)

Merge branch '176-add-neutron-star-merger-to-examples' of https://git.ligo.org/Monash/tupak into 176-add-neutron-star-merger-to-examples

Revert "Merge branch '176-add-neutron-star-merger-to-examples' into 'master'"

See merge request Monash/tupak!182

This reverts merge request !171

Resolve "add neutron star merger to examples"

See merge request Monash/tupak!171

Previously variables with a fixed (or delta function) prior where not
added to the posterior data frame; the documentation for
`samples_to_posterior` indicates that this is the case. This resolves that.

Add flake8 checker

See merge request Monash/tupak!177

# Conflicts:
#	tupak/core/result.py

# Conflicts:
#	tupak/core/result.py
#	tupak/core/sampler.py
#	tupak/gw/detector.py

Resolve "Add more __repr__ methods"

Closes #160

See merge request Monash/tupak!170

Resolve "Improve PowerSpectralDensity structure"

Closes #177

See merge request Monash/tupak!173

Adds a simple example of using gwin for an injection

See merge request Monash/tupak!166