Object being passed for string in printf-style statement

Newest version of Vala apparently catches this (older versions
compiled w/o complaint).  Caught by GNOME Continuous.
Stabilize sort of search email identifiers: Bug #733271

Without stabilization, it was possible for multiple emails in search
results with the same INTERNALDATE to be dropped due to the equality.
Patch major memory leak due to GMime bindings

Discovered a few binding problems while working on another issue,
in particular gmime_parser_construct_message()'s return object
not being freed, which can hold an entire message (attachments and
all) in memory.
Only report Inbox deselected if Inbox is being removed: Bug #727744

Changing a specal folder type involves adding and removing the folder
entry in the folder sidebar.  Prior logic would look in the Inboxes
branch if the entry was not selected in the "normal" account branch
but not verify the folder in Inboxes was the one being removed.  This
triggered an unwarranted "nothing selected" signal that caused the
conversation list to go blank at startup when Geary was associating
special folder types with folders.

Note that you must have multiple accounts registered w/ Geary to
trigger this bug.
Update to 0.6.2