Event optimize cleanup

[devbhakt]

Removed obsolete code that is no longer being used within event_optimize

• Manually tracking the progress of the MCMC run has been removed since the emcee sampler has a built in progress bar
• Global tracking of the maximum posterior has been removed as it was not working properly with parallel processing and the maximum posterior values were switched to being calculated using the metadata within the emcee sampler in the original parallel processing implementation.
• Removed the custom timing class as it is not being used

Moved the portion of the code that generates a TOA object and weights from the photon data into a dedicated function.

• The function loads in the photon data, creates a TOAs object using the photon data between the passed min and max MJD arguments, and the corresponding photon weights.
• Removed the usepickle argument as the function checks the events file name to determine it is a pickle file or not.

[abhisrkckl]

Please add a CHANGELOG entry

[abhisrkckl]

Can you please check why the documentation build is failing?

[abhisrkckl]

I think the issue is having the line ---- above the heading in the docstring (like Parameter) rather than below it.

[devbhakt]

Should be fixed now! Thanks @abhisrkckl

[devbhakt]

All tests have passed and the PR is ready for review