Routine shellMsg() is the last one executed in the input loop. It waits for a new key, acting upon the following:-
- adds alphanumeric keys to the command line
- left-arrow .. shift left
- right-arrow .. shift right
- backspace .. shift left and insert blank
- Ctrl-k .. clear the command line
This feature does nothing yet with the result. Use Ctrl-O to get a shell for now.
