Enhancements:
- exchange2grommunio: add robust file lock detection for exported PST
- exch: avoid re-use of Message-Id when message is submitted twice
- pff2mt: do not choke on NO_ATTACHMENT objects (resolves PF-1012 warning)
Fixes:
- emsmdb: oxcfold_deletemessages had incorrectly tested for PR_READ
- emsmdb: fix OL entering infinite loop deleting messages with read receipt requests
- zcore: PR_SENT_REPRESENTING_SEARCH_KEY was not set on submit
- exmdb_provider: restore fxstream ability to read PT_OBJECT attachments
- emsmdb: resolve a case of synchro repetition occurring in clients
- rpc_lib: clear NTLMSSP_CTX and resolve a crash due to garbage pointers