Moved conversions into separate functions can2pty() and pty2can().
Updated and enhanced some comments.
Variable name cleanups inside the separate functions.
Fix handling on wrong pty commands (was a wrong 'continue' statement).
creates a pty for applications using the slcan ASCII protocol and
converts the data to a CAN network interface (and vice versa).
This can be used for existing applications to run on SocketCAN.