Allow plugins to perform asynchronous port detection, and to defer port detection
until later. This moves the prober bits into MMPluginBase so that all plugins
can take adavantage of it only when needed; the probing is not done at udev time.
Furthermore, plugins like Novatel can flip the secondary ports over the AT mode
through deferred detection, by deferring the secondary ports until the main port
has been detected and AT$NWDMAT has been sent.
This commit also finishes the port of the rest of the plugins (except mbm) over
to the new port detection methods and plugin API.
Otherwise, if something else is mistakenly holding the serial port open at
the same time as this MMSerialPort, you get a stream of reads of size 0 and
effectively hang modem-manager.
Get rid of dependency on HAL, using libgudev instead. Fix up the plugin API
to no longer use either HAL or udev defines, but let plugins use whatever
mechanism they want for getting more information out of the device given the
subsystem and device node name.
Modems are now defined as "master" devices which "own" a one or more ports.
A port could be a serial tty device or a network device or whatever. The
plugin figures out whether it supports a given port or not and then assigns
it to a new or existing modem. Modems now have a 'valid' property that
should be set to TRUE when the modem has enough ports to operate correctly.
For devices (ex. 'hso') that use a network device for data transfer, the
modem would need to grab at least one TTY and the network device associated
with that physical device to be 'valid'.
Also move the generic modem support code to a plugin like other modem plugins,
and change the I-support-this-device mechanism to return a number indicating
the level of support. For example, the generic plugin would return a quite
low number if the device indicates via probing that it can do GSM or CDMA, but
a more specific plugin can indicate better support for the device, and thus
the more specific plugin would win control.
