[patch 1/6] Add PPP protocol support with HDLC framing

[Denis Kenzior]

Hi Kristen,

> +struct ppp_link * g_at_ppp_new(GIOChannel *modem);
> +void g_at_ppp_open(struct ppp_link *link);
> +void g_at_ppp_set_connect_function(struct ppp_link *link,
> +			       GAtPPPConnectFunc callback, gpointer user_data);
> +void g_at_ppp_set_disconnect_function(struct ppp_link *link,
> +				  GAtPPPDisconnectFunc callback,
> +				  gpointer user_data);
> +void g_at_ppp_shutdown(struct ppp_link *link);
> +void g_at_ppp_ref(struct ppp_link *link);
> +void g_at_ppp_unref(struct ppp_link *link);

Almost forgot, let us not use struct ppp_link here, but instead use GAtPpp 
*ppp as the parameter.  Again, mostly for consistency with how glib / gatchat 
does this.

Regards,
-Denis