output_pin: Deprecate static_value parameter

Remove support for configuring "static" pins in output_pin module.  A
"static" pin only saves a few bytes of memory in the micro-controller.
The savings does not justify the increased code complexity.

Deprecate the static_value parameter to warn users.  In the interim, a
static_value parameter will set both value and shutdown_value
parameters.

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

config/generic-ultimaker-ultimainboard-v2.cfg

@@ -97,7 +97,7 @@ max_z_accel: 30
 
 [output_pin case_light]
 pin: PH5
-static_value: 1.0
+value: 1.0
 
 # Motor current settings.
 [output_pin stepper_xy_current]
@@ -107,7 +107,7 @@ scale: 2.000
 # Max power setting.
 cycle_time: .000030
 hardware_pwm: True
-static_value: 1.200
+value: 1.200
 # Power adjustment setting.
 
 [output_pin stepper_z_current]
@@ -116,7 +116,7 @@ pwm: True
 scale: 2.000
 cycle_time: .000030
 hardware_pwm: True
-static_value: 1.200
+value: 1.200
 
 [output_pin stepper_e_current]
 pin: PL3
@@ -124,4 +124,4 @@ pwm: True
 scale: 2.000
 cycle_time: .000030
 hardware_pwm: True
-static_value: 1.250
+value: 1.250