Remove excess `require' call.
Add commentary, do some other various cleanup.

- Edit description for brevity
- Add commentary
- Fix `cl' loading
- Clean up customization group definition
- Fix capitalization in keychord definitions
Update HTTP request and response functions (and their docs).
Finished a TODO item.
Remove dead code from `anx-authenticate' (and update docstring).
Silence byte compiler's warning about `url-http-end-of-headers'.
Remove dead code in `anx--pop-up-buffer', silencing byte compiler.
Fix last compiler warnings (due to free variables).