Choose a better name for the key handling function.

The key handling function does much more than simply exiting when "q" is
pressed, so give it a better name than "exit_on_q".

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Simplify key handling code.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>