Added load command to Morse code interface. Fixed various other things.

Made O in Morse code load the saved settings as previously documented.
Slowed the default dit duration. Updated voltage monitor calibration.
Made timeout for reading or copying input abort leaving the previous
value unchanged rather than assigning a null/0 value. Fixed a prompt
for the high voltage threshold that said "low". Made the command to
report the top of the stack first pop the command token off the stack.
Removed the QSR command to avoid confusion with QRS. Made the radix for
string to integer conversion explicitly 10 because there is no reason
to support syntax like 0xA4.