Rename printer.gcode.action_emergency_stop() to
action_emergency_stop(), printer.gcode.action_respond_info() to
action_respond_info(), and printer.gcode.action_respond_error() to
action_raise_error() in command templates.
This simplifies the get_status() interface, as returning callable
functions from that interface was confusing.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>