[features added]
* Serial: Inbound connections are now supported.
* Serial: Added support for A, L, M, P, Q, S, T, V, X, &C, &D, &F, &G, &P, &T, &V, and &W modem commands.
* Serial: Added DTR and CRX signal support.


[bugs fixed]
* GTIA: Fixed trigger state sometimes being initially wrong when enabling latching.
* Serial: Telnet emulation now reads out of band data.
* Serial: Telnet emulation now handles incoming WILL and WONT commands.
* Serial: Fixed sporadic missing newlines on modem status messages.
* Serial: Control line state is now reported in non-concurrent mode.