Refactor the send code

Previously, sending worked by decoding a string which encoded
a binary or tristate codeword. Trying to send a bit pattern directly
(encoded as an integer) involved turning it into a string first.

This is a waste of memory and CPU cycles. So we do it the other way
around now: The central send() function accepts an integer containing
the bit pattern to be sent. The other send() function which takes
a 0-1-string, as well as sendTriState(), now call this new central
send() function. Incidentally, this reduces code duplication and enables
further refactoring.