* Verbose logging. * Cookie needs a path. * Configurable callback URL. * Various sanity checks.
GitHub implements OAuth2, but not OpenID Connect. This means it needs more magic constants than those that can do OIDC discovery (and where Userinfo is in OIDC-compatible.) Fixes the HTTP client to have a timeout.
This is forked from @anandv96's #1374. Closes #1297.