Overhaul search() signature and docs

[Mr0grog]

⚠️ Breaking Changes! ⚠️

The signature for search() was unwieldy, complicated, and included a bunch of parameters that did nothing or that might cause broken behavior and should never be used (e.g. page and pageSize). While adding a default value for limit to resolve #65, I went ahead and cleaned up search():

• Adds a default value for limit in order to fix a very bad footgun. (See Add a default limit to WaybackClient.search() #65)
• Adds a lot more detail to the docs, explains special formatting for url and complex considerations for limit.
• Removes non-functional or breakage-prone parameters that were only included because they were part of the HTTP API. In some cases, they are things this library does automatically for you and aren’t useful to adjust (e.g. gzip), in others you could break things (e.g. page and pageSize), and some are implementation details that users shouldn’t be bothered with (e.g. resumeKey, previous_result).
• Removes the ability to specify arbitrary extra keyword parameters to be passed directly to the API (there are so many ways to break things here; I argued for this originally so we didn’t have to maintain as much, but it’s just not good).
• Makes all parameters use snake_case.

Internally, the only real change is that this is now a loop instead of a recursive call. This was required in order to not expose internal details as parameters, but is also probably better for call stack and memory management on large queries.

Fixes #65.

@edsu are these API changes going to be OK for you? I’ll make sure this is released as 0.4.0 rather than 0.3.x. If you have any feedback on the docs changes, too, I’d appreciate it (you can preview the build docs from the “checks” at the bottom of the PR).

I might also try to include a first pass at #8 before releasing.

[Mr0grog]

Note: the size reduction here is mostly because recorded responses for tests are gzipped, which was not the case before. (I think what happened is that the CDX server now respects the Accept-Encoding header, which we have always sent, instead of only using the gzip query parameter, which we do not send.)

[edsu]

I like these changes to simplify usage and guide users down the happy path -- also the snake_case changes are most welcome.