[mms] Don't display empty mailbox action for mailboxes when Virtual Trash is active (Bug #12162).
Use getContentTypeParameter() to retrieve current boundary (Bug #12161).
[mms] Add Horde_Support_CaseInsensitiveArray class.
[mms] Content-Type parameters are case-insensitive (Bug #12161).
Expire cached mailbox lists when switching to/from virtual trash
Merge branch 'for_upstream' of github.com:sathieu/horde into sathieu-for_upstream