Allow plugins to specify that signal quality/access tech polling isn't needed (v2)

[Aleksander Morgado]

Hey Dan and everyone,

This patch series contains the following updates w.r.t. the v1 patches:

 * When a explicit signal refresh is requested, setup the initial fast-polling configuration (this was suggested in the review of PATCH 2/4, but the fix has been applied in PATCH v2 1/4).
 * In the Cinterion plugin, Use G_N_ELEMENTS() when iterating ports array setting up unsolicited message handlers.
 * In the Cinterion plugin, check support for SIND/psinfo and if it isn't supported, don't bother enabling or disabling those unsolicited messages any more.

    [PATCH v2 1/4] iface-modem: consolidate signal quality and access tech
    [PATCH v2 2/4] iface-modem: if bands, capabilities or modes change,
    [PATCH v2 3/4] port-serial-at: always prepend unsolicited message
    [PATCH v2 4/4] cinterion: use ^SIND unsolicited messages for access tech

Comments?

--
Aleksander