Update list of TODO RFCs
[mms] Added support for sending internationalized header data (RFC 6531).
update documentation
[mms] Internally handle capability querying via the new Horde_Imap_Client_Data_Capability object.

This is BC with current API, since we still return array information for
public methods.  But these methods are deprecated and have been replaced
with a single endpoint - the Capability object - that should be used
going forward (and is used exclusively internally).

This fixes a few edge cases, and consolidates some duplicate code that
wasn't quite identical. Allows unit testing of the capability
querying code.
[mms] Fix debug logging for certain IMAP authentication actions.

For actions that required continuation responses (whether they were
actually used or not), the entire command and related internal debug
info (e.g. capabilities that are ignored) was being lost.

Additionally, allows more granular masking of commands. Debug output now
displays as much of the actual command as possible other than the
authentication credentials.