Curse these manual processes.

A couple of queries (at least the search blacklist query and the folders
for each email query) weren't respecting the flag in
MessageLocationTable that means we should treat the row as if it didn't
exist.  This was causing problems where a draft that was also a search
result would keep being duplicated in the search results as you typed
more in the draft.  The cause was that the removed signal was fired
after the message had been marked as removed, but before it was actually
deleted, so it was still being found in the search even though
folderless emails are blacklisted.

Closes #6380 Closes #7518 Welcome dialog can be safely closed, invalid password will not be saved to keychain

count - 1 is being used to pick the ngettext() call, but count was
being passed in.

Old message wasn't clear if the number of additional new messages
was in addition to the one being reported or total new messages.
Additional new messages is a more interesting value, so this changes
the value to additional and the message to clarify that.

* Increase the size of the spinner; fix #7184
* In the event of an error sending a message, display text in the status
  bar indicating as such (and display a notification too); fix #7481
* Display a status bar message and spin the spinner when sending;
  fix #4629
* Re-add the sound played when a message is sent; fix #5429

This takes advantage of Outlook.com's new IMAP support, meaning
Geary works with Outlook.com, Hotmail, and Live.com users.

Because Outlook.com doesn't support UIDPLUS, some features
(in particular, draft auto-save) is unavailable, as is the
ability to use its Archive folder directly.

This patch fixes a couple of bugs that occur when a server doesn't
support UIDPLUS.  Also fixes a use case with UID increment/decrement
that caused a flag watcher bug due to ImapDB.Folder always
returning the same email if only one was present in the folder.

ImapEngine.GenericFolder.internal_close_async() was hanging due to
the ReplayQueue never closing.  This could occur if there was a
hard error (i.e. network) while opening the Folder.  In essence,
this hung Folder.open_async(), which put the client into a bad state.

Now the ReplayQueue doesn't hang and is flushed if a "clean" close,
while outstanding operations are dropped if closing due to an error.

This also includes some small fixes in ClientSessionManager to
prevent a hang due to mutex reentrancy, and a State problem in
ClientSession that is unrelated but bad enough that it should be
included here.

strip_prefixes() should use decoded string, not original, otherwise
the encoded Subject is returned.

This also properly strips both Re: and Fwd: prefixes, even when
stacked up, in the conversation list.

Definition of "new messages" is misleading, now always describing
message details unless more than one arrives at the same time:
Closes #7376

When multiple messages arrive, note which account they arrived
for: Closes #7386

Show more information about new messages in notifications
(specifically, if additional new messages have arrived for account,
include summary of number): Closes #6952

Deprecations are now enabled.  This will have to hold until we
rewrite Geary's UI not to use the various widgets being deprecated
by GNOME.

Engine validation now takes options flags indicating if the
validation is for adding or editing an account, and if the
network connections need to be checked.

Ctrl+S gives the Search box focus.  Tooltip text added to the
Search widget.

Some reorganization of how data: URIs are assembled and injected
into the document.

Also, mild improvement to the GMime bindings.

Replaced images are converted into data: URIs, so this change
involves saving in-memory buffers rather than copying attachments
out of the attachments directory.

It was a good idea in theory to trigger an append when search results
are first added, but this hits the conversation monitor too hard, which
can't easily handle large appends (ticketed at #7464).

This also updates the conversation monitor to listen to the new inserted
signal instead of looking at count-changed.