Compiling EDS with --disable-shared was broken due to several global
variables being declared with the same names, and not being declared
static. Fix that by eliminating the unused ones and making the rest
static.

https://bugzilla.gnome.org/show_bug.cgi?id=752233

Thus filtering like check for junk can be stopped earlier, not only
after all messages are tested.

Use mail-disabled, calendar-disabled and contacts-disabled properties,
rather than rely on an interface addition/removal and a notification
about the change.

Reported at https://bugzilla.redhat.com/show_bug.cgi?id=1242541

The problem was that locale_supports_12_hour_format() returned failure
when the locale supported 12 hour format, because the AM/PM string
didn't fit the 16-bytes buffer. Using large-enough buffer and sane
'struct tm' values makes this work properly. One such locale is bn_IN.

If not done, then the old ESource-s could be forgotten and a new added,
despite the old being available, which has consequences like local
cache of these ESource-s re-population and similar.

When the folder, or the account, is not set to be synced for offline,
set the cache expiration for one week, thus the local cache doesn't
blow indefinitely when the user doesn't want offline access to
downloaded messages.

These are collection sources, thus not necessarily also WebDAV or
with an Authentication extensions, but at least the WebDAV extension
is used for auto-discovery and SSL Trust result reading, thus make
sure the extension is there, thus the prompt result is saved as well.

It was made optional earlier, but the code still required it.

Philip Withnall authored Jun 16, 2015 and Philip Withnall committed Jun 18, 2015

We do not want the following two calls to behave differently:
   e_vcard_attribute_new ("", "X-HELLO")
   e_vcard_attribute_new (NULL, "X-HELLO")

Elsewhere in the vCard code, attribute group names are guaranteed to be
NULL or non-empty strings, so we should follow that precedent here.

https://bugzilla.gnome.org/show_bug.cgi?id=751044

When available, reuse existing source, thus all the changes are not
done on an object which is immediately freed.