mod_http_oauth2: Reject duplicate form-urlencoded parameters Per RFC 6749 section 3.1 > Request and response parameters MUST NOT be included more than once. Thanks to OAuch for pointing out Also cleans up some of the icky behavior of formdecode(), like returning a string if no '=' is included.

This module discards typing notifications sent to a bare host JID,
preventing error replies to be sent. These errors are harmless but can
be annoying sometimes if your client shows them prominently.