Hotkey mode:
new key: $config->{hotkey_condvar}
handle hotkey Escape in dispatch table
Escape to cancel multikey input
Enable grammar for processing multikey input
Map arrow keys
end_of_list_sound()
hotkey commands: set_stepsize, increment_param, decrement_param
  this_param(), this_stepsize()
  check before method calls in $Event::DIED handler
list key
hotkeys: new mappings
Track: new method pos() gives current op position
use hotkey "m" to set multiplier (stepsize)