Add government lookup requests

[dcragusa]

A function that returns a list of tickers corresponding to a generic govt. security such as 'T Govt'.

I don't feel comfortable opening a pull request due to so many style changes, but an implementation can be found in my fork here.

[matthewgilbert]

This looks interesting. I agree that a pull request in its current form wouldn't make sense since there is a lot going on here and I prefer sticking to atomic commits. Reproducing from your commits I see the following changes:

• Add type hints
• Refactor receiving events
• Simplify message parsing
• Robustify function arguments
• Add govt list function and test coverage
• Style changes
• Allow for changing host in unit testing

When I get some spare time I will look to incorporate some of these changes. I think most things look good although I will likely hold off on introducing types since this is a fairly major change and I would like to give it some thought prior to introducing the change. I would be happy to receive atomic commits on any of the above changes excluding the type hints.

[dcragusa]

That sounds good, I will make a separate branch with atomic commits sans type hints.

[matthewgilbert]

@dcragusa Some of these are now done. The features from your branch I have incorporated in recent commits 8340f324d91145255cc1c8df797cb66ad82bd073, d78791d2330949b74b41e9e196def75fc4758dba, c3ae2e5aea8afd762dc36c464e6eb1b5002b2542 are:

• Refactor logger setup to improve clarity
• Refactor event handling into _receive_events()
• Allow changing host in conjunction with general refactoring of tests to use pytest

[dcragusa]

Excellent, I will PR the govt list function soon.