GitLab

1) Add axes labels
2) Add individual p values to the legend
3) Use latex labels

Additionally add the p-value to the plot in a title

Also resolves minor bug with likelihood meta data

Useful if the pvalues needs to be logged elsewhere from a script

- Also adds function to figure out the signal duration, closes #77

- Add legend/colors for each parameter

Minor improvements to the handling of data saving to disk
1) Writes a result file before and post-processing to ensure data isn't
lost
2) Internal rejig of how the logic of which result file to write is
checked
3) Dumps the dynesty result object to disk (for most other samplers a
simple cache file is produced automatically)