Implement connect, disconnect, and IP4 config stuff.
Also fix handling of Icera private data. After creation we
need to use MM_MODEM_ICERA_GET_INTERFACE(m)->priv to get the
private data instead of just dereferencing the MMModemIcera,
for reasons that I don't know. If this isn't done, data
gets silently corrupted because writes to the private data
are going into a random location in the object. This a
side-effect of the slightly hack-ish way that MMModemIcera
is a GInterface with private data.
Dan Williams