Using a new ESourceRegistry and freeing is slightly afterwards could
left some unfinished operations in the sourec registry's main_context.
A change for this lands in evolution-data-server, but better to change
also evolution-ews, to not create the source registry when not necessary.

Without that the mail account Preferences take whole screen width
with gtk 3.14.x.

The first is checked for on many places in the UI, while the later
is not checked anywhere. The outcome was that a cancelled operation
added a warning in the UI about "Operation Cancelled", which is
useless.

The translation should be merged into the appdata related files.

This is useful for GNOME Software, to show the plugin as an addon
for the Evolution. The used translatable strings are taken from
the camel provider.

(cherry picked from commit 8e69c824)

(cherry picked from commit 76e21be0)

Fix broken g_object_unref() on strings in the failure case too.

(cherry picked from commit e117c807)

(cherry picked from commit b5cc807e)

Stop it being so much of a special case; just populate an 'items to be
deleted' list with everything that's currently known, set the sync_state
to NULL and loop again.

(cherry picked from commit c3c88442)

We don't use this any more...

(cherry picked from commit 524f2910)

Once we start doing locking, we'll want the whole update to happen in
one transaction, so do all the network access first.

(cherry picked from commit 3effacde)

... and fix up e_book_backend_ews_get_contact_list() to cope.

We'll actually want to ditch the store_to_cache mode of ebews_fetch_items()
and *always* use it to return EContacts, even from ews_update_items_thread().
That way we can do all the network I/O in advance and then do the database
update in a single transaction.

Fix a crash in the database-query code paths in get_contact_list() too while
we're at it. On converting to EBookSqlite, the 'list' variable needed to be
initialised to NULL.

(cherry picked from commit 8827df5c)

When we add cursor support, it'll depend on this...

(cherry picked from commit 588f1b44)

When we add cursor support, it'll depend on this...

(cherry picked from commit c8b18a75)

If we register the same type from two *different* modules, the type
system gets upset. That's precisely what happens if we enable addressbook
DRA, because the addressbook and camel modules both get loaded into the
same process.

So make it a normal static class. We do have to use g_type_ensure()
though, because e_source_get_extension() will look it up by name,
iterating over the child classes of ESourceExtension.

(cherry picked from commit addd8f6c)