Fix draw.path and improve documentation

[a-hurst]

Fixes a bug with the pure Python wrapper (and documentation), where Draw.path was documented in the original effbot docs (and thus implemented in the wrapper) as having both an xy parameter and a path parameter, just like Draw.symbol. However, this is no longer the case as of this patch 11 years ago (c7cac6c), which separated the path and symbol methods and removed the xy parameter from the path method, which effectively broke the path method wrapper.

This PR fixes the issue as well as cleans up the docs around Draw.path and Draw.symbol for a bit more clarity (and adds a unit test for Draw.path).

[a-hurst]

Looks like tests are failing due to some conda connectivity issue? I can't re-run them as a non-member but if you re-run them manually everything should pass!