Add support for parsing path parameters with file extensions, etc.

[makdad]

As I wrote in interagent/committee#261 - my path of fribble/{id}.json failed to match because the OpenAPI parser expected that path parameters be "by themselves" (e.g. fribble/{id} or fribble/{id}/details.json). The legacy API I am modeling is unfortunately not this way.

I am opening the issue again on this repository because the root fix is in the parser, not in Committee.

I've made progress on a pull request to address this issue, but unfortunately it breaks some other tests. I am still looking into this, but I wanted to create the issue here, as well as post a link to the PR, so that I could begin to receive some feedback from the maintainers.

My first attempt:
https://github.com/makdad/openapi_parser/pull/1/files

[makdad]

I think we can close this issue, as #90 was merged into 0.12.0, so I think this is "fixed as of 0.12.0"?