Added explicit garbage_collect.
Use partitions for mam_message.
Use binary collation with MAM tables.
Fixed a tiny bug in mod_mam_mnesia_dirty_prefs.
Added modMamForwarded metric.
Optimized messages' extracting before known id.
Fixed a tiny bug in mod_mam_mnesia_dirty_prefs (again).
Added mam_message.i_mam_message_uid index.
Added index hints for MySQL.
Do not add <forwarded/> if message is not archived (dropped).