Add Support for Bizhawk's comm module

As it is, Bizhawk prepends every command with the number of bytes of the sent message; i.e. sending "starttimer\r\n" actually sends `12 starttimer\r\n`. It would be helpful if this module could accept this format, especially since I imagine interacting with Bizhawk is a common use case for this module.

Start by locating the comm module and the code that parses incoming commands. Trace how the existing command format is read, then verify that a byte-count prefix such as `12 starttimer\r\n` is accepted while the command and line ending remain usable. Done means Bizhawk's prefixed messages work through the module.

Written by the indexing model from the issue text.