Add search endpoint method

[mr-devs]

Originally, I was going to try and build a more structured framework that allowed users to pass, for example, a list of keywords or hashtags or cashtags (etc.), and then have the method build the query. However, building something that can capture the entire functionality of the endpoint package seems like serious overkill. Furthermore, I toyed with the idea of providing some sort of simple functionality (like being able to accept a list of keywords), however, I think this makes things more confusing.

Instead, I provided a lot of details in the docstring which should be sufficient for anyone with half an idea.

This way the user can build the query themselves and pass it directly to the method.

Note: the tests.py document now includes a test that utilizes an endpoint that is only available for those with academic track access! You can simply comment out line 130 in the file and run that way to test without this level of access.

[mr-devs]

Subsequent testing revealed a few bugs in the rate_limit_manager.py script. The temp-mix branch is more up to date. I'm going to close this and the rate limit branch branch because they are behind that one.