The whole codebase is updated to assume the MMBaseModem AT operations
require an object implementing the MMIfacePortAt interface, instead of
a MMPortSerialAt object.
In the places where we know the port is a MMPortSerialAt, e.g. when we
query explicitly for the primary or secondary serial AT port, we will
use an explicit MM_IFACE_PORT_AT() cast when calling the AT command
method.
In the places where we get_best_at_port() we're going to assume that
we don't know the port type. This method will be updated in a follow
up commit to support the MMIfacePortAt interface as well.
We are going to allow including the plugin sources built within the
ModemManager daemon binary; moving the sources within the daemon
sources directory makes it easier.
Aleksander Morgado