core: fix casting of factory type (bgo #736780)

UINT is just 32bit, truncating the GType on 64-bit platforms. We do already use
cast to SIZE, which is as wide as a pointer, when we need a GType in another
place (nmtui); let's do it here as well.

Broken by [0bc1b5138] core: add support for internal device factories

https://bugzilla.gnome.org/show_bug.cgi?id=736780
Revert "tui: fix a crash"

This reverts commit c0ecd2f62815606824bc934599dc46b069fe9962.
libnm-core: fix getting/setting 0-length array properties

Empty array-valued properties should return a 0-length array from
get_property(), but should also accept NULL as equivalent to a
0-length array from set_property().
libnm-core: drop the ability to verify settings from property overrides

It needs to be possible to deserialize a connection hash into an
invalid NMConnection; in particular, AddAndActivateConnection()
explicitly allows this.

Previously, the SetFunc and NotSetFunc passed to
_nm_setting_class_override_property() could return a verification
error immediately, but this functionality has to go away if we're
going to be able to deserialize invalid connections.

That functionality was only used in the handling of invalid virtual
interface names; reorganize how that code works so that
NMSettingConnection does all of the verification itself. (The code to
make sure that it returned the "correct" error domain in that case
turned out to be irrelevant, since the setting error domains don't get
serialized over D-Bus correctly anyway.)
libnm-core: fix up connection deserialize/copy/replace semantics

libnm-util's connection deserializing/copying/replacing functions have
odd semantics where sometimes they both modify a connection AND return
an error. libnm-core tried to improve things by guaranteeing that the
connection would not be modified if the new settings were invalid, but
this ended up breaking a bunch of places that needed to be able to
work with invalid connections. So re-fix the functions by reverting
back to the old semantics, but having return values that clearly
distinguish whether the connection was modified or not.

For comparison:

  - nm_connection_new_from_hash() / nm_simple_connection_new_from_dbus():

      - libnm-util: returns a valid connection or NULL.

      - OLD libnm-core: returned a valid connection or NULL.

      - NEW libnm-core: returns a valid connection or NULL.

  - nm_connection_duplicate() / nm_simple_connection_new_clone():

      - libnm-util: always succeeds, whether or not the connection is
        valid.

      - OLD libnm-core: returned a valid connection or NULL

      - NEW libnm-core: always succeeds, whether or not the connection
        is valid.

    - nm_connection_replace_settings_from_connection():

      - libnm-util: always replaces the settings, but returns FALSE if
        the connection is now invalid.

      - OLD libnm-core: either replaced the settings and returned TRUE
        (if the settings were valid), or else left the connection
        unchanged and returned FALSE (if not).

      - NEW libnm-core: always replaces the settings, and has no
        return value. (The modified connection is valid if and only if
        the replaced-from connection was valid; just like with the
        libnm-util version.)

    - nm_connection_replace_settings():

      - libnm-util: returns TRUE if the new settings are valid, or
        FALSE if either (a) the new settings could not be deserialized
        and the connection is unchanged, or (b) the new settings were
        deserialized, and the connection was updated, but is now not
        valid.

      - OLD libnm-core: either replaced the settings and returned TRUE
        (if the settings were valid), or else left the connection
        unchanged and returned FALSE (if not).

      - NEW libnm-core: returns TRUE if the connection was updated
        (whether or not it is valid), or FALSE if the new settings
        could not be deserialized and the connection is unchanged.
libnm: fix object-creation-failure code

If _nm_object_create() hit an error, it would return the
(half-initialized) object anyway. If _nm_object_create_async() hit an
error, it would return NULL, but leak the half-initialized object. Fix
both cases.
libnm: drop two unnecessary NM_IS_OBJECT() checks

Now that NMRemoteConnection is an NMObject, the code only creates
NMObjects, so we don't need that check.
libnm: fix race conditions when creating the same object twice

If two code paths try to asynchronously create the same object at the
same time (eg, because it shows up in two different properties), we
are supposed to deal with that. But at some point a race condition
appeared where we could end up returning a partially-initialized
object for one of the properties in the async case. Fix that.

Also add comments to both the sync and async cases explaining why they
work the way they do.
Misc libnm-core fixes (bgo #736700)
tui: fix an out-of-date comment

nmtui-connect.c claimed that it didn't implement deactivation yet, but
that was implemented long ago.
libnm-core: fix nm_connection_replace_settings()

The rewrite mistakenly used nm_connection_add_setting() rather than
_nm_connection_add_setting(), causing it to emit the "changed" signal
while the connection was only partially rebuilt.
libnm-core: fix crash while converting permissions to list

Accept NULL as equivalent to a 0-length array from set_property().
callouts: port nm-avahi-autoipd.action to GDBus
libnm-core: add GVariant-based versions of IP structure-manipulating utilities
dispatcher: trivial code rearrangement

Reorganize some code in preparation for the GDBus port. (Most of the
diff is actually just reindentation.)

This also makes explicit something that was probably a bug;
IP4_NUM_ROUTES is always set, even if it's "0" (while the same is not
true of IP6_NUM_ROUTES). (This behavior is preserved for
compatibility.)
dispatcher: port to GDBus

Port nm-dispatcher to GDBus, mostly, using dbus-glib's GVariant
utilities to translate the return value of nm_connection_to_dbus().
dispatcher: make test-dispatcher-envp not take an argument

Compile srcdir into test-dispatcher-envp rather than passing it on the
command-line, to make it easier to run by hand, and so we can use
automake's TESTS support.
Port callouts to gdbus (bgo #622927)
tools: fix test-networkmanager-service Settings.Connections

The test settings service wasn't exporting a Connections property.
libnm: merge libnm-vpn into libnm

There's not much point in keeping them separate: all existing
libnm-glib-vpn users also link against libnm-glib, and the amount of
extra code added to libnm by merging in libnm-vpn is negligible.

Additionally, nm-vpn-plugin will later need access to some
libnm-internal APIs.

So, merge them together.