Add Support for Bizhawk's comm module

[cjheskett]

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.