Respond with something more interesting than echo

* Decode base64 string if the received string starts with 'b64'.
* Respond with 'yoo!' if the received string was 'icky'
* Respond with inversed string otherwise
Script that should act as a little serial console

It doesn't work properly yet for some reason. Whatever it sends is
interpreted as 'misc' command and gets reversed, 'icky' and 'b64'
commands don't work like they should. But they do work when connecting
with screen, so the problem is on this script's side, not the other end.