When a command in the tmux source code block ended with a semi-colon,
it was previously ignored. Now we send the keys with the -l option to
send the line literally.
It is now possible to create multiple windows in the same
session. One can write, for example,
echo boom
echo done
This will open up a terminal window with one tmux session, named
'hello', and two windows, named 'boom' and 'done'.
Tests the tmux functionality. Also solves some problems in the
original implementation where the temp file would be read directly
after creation, i.e. before the random string could be written to the
file.