pwm_tool: Add support for high-speed PWM pin updates

The output_pin module is only capable of updating an output pin at
most once every 100ms.  Add a new pwm_tool module that is capable of
queuing updates in the micro-controller and thus allowing for much
higher update rates.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/sample-pwm-tool.cfg

@@ -2,9 +2,8 @@
 # such as a laser or spindle.
 # See docs/Using_PWM_Tools.md for a more detailed description.
 
-[output_pin TOOL]
+[pwm_tool TOOL]
 pin: !ar9       # use your fan's pin number
-pwm: True
 hardware_pwm: True
 cycle_time: 0.001
 shutdown_value: 0
@@ -36,9 +35,9 @@ gcode:
 
 [menu __main __control __toolonoff]
 type: input
-enable: {'output_pin TOOL' in printer}
+enable: {'pwm_tool TOOL' in printer}
 name: Fan: {'ON ' if menu.input else 'OFF'}
-input: {printer['output_pin TOOL'].value}
+input: {printer['pwm_tool TOOL'].value}
 input_min: 0
 input_max: 1
 input_step: 1
@@ -47,9 +46,9 @@ gcode:
 
 [menu __main __control __toolspeed]
 type: input
-enable: {'output_pin TOOL' in printer}
+enable: {'pwm_tool TOOL' in printer}
 name: Tool speed: {'%3d' % (menu.input*100)}%
-input: {printer['output_pin TOOL'].value}
+input: {printer['pwm_tool TOOL'].value}
 input_min: 0
 input_max: 1
 input_step: 0.01