- port rs232.h code to new serial.h cc65 API, so we aren't stuck using
  old versions of cc65.

- tab-completion, by searching screen memory?

- a bit of UTF-8 decoding. e.g. accented letters become 2 characters.
  Spanish enya would be rendered as n, inverse ^ (since inverse ^ is
  what we already use for the ~). Letter a with acute accent would
  be "a" and "'", with grave accent the "'" is inverse. Degrees symbol
  would be inverse lowercase o. Ellipses would just be 3 dots. Anything
  we can't decode becomes inverse question mark. It would be really nice
  to encode/decode the ATASCII graphics characters too.

- support 'terminal server' devices, e.g. lantronix. These are devices
  with an rs232 port + tcp/ip stack. Clients just talk rs232 and
  the terminal server connects that to a remote host via TCP. Some
  of these emulate modems (ATDT<ipaddress> for instance). Will require
  some major surgery to split the SLIP stuff from the IRC protocol stuff.

- support Dragon cart (or the other Ethernet cart, or the wireless one).
  have to somehow get the hardware to test with first.