- When the last call (the one which makes the receiver get the EOM) generates
  multiple rings, the second ring is seen as the first ring of the first call
  in a new message. See if there's a way to improve that.
- Use lists for the currently received symbols and signals instead of a single
  string for the received message. This would make it easier to print partial
  results.
- Consider making Modem.py and MorseTranslator.py independent packages.
- Add a better command line argument parsing for the transmit.py and
  receive.py programs, or even better unify them in a savemysugar.py program.
- Do not use Modem.py directly in the transceiver class but instead use
  a generic transmitting/receiving back-end in order to support other
  transmission mechanisms or telephony frameworks with python bindings (e.g.
  freesmartphone.org).