Switching GPIOPWM to on tries to create a new PWM object

[PaulKGrimes]

Every time GPIOPWM.on() is called, it tries to create a new PWM.GPIO object, attached to the actor's GPIO pin (line 56 of modules/base_plugins/gpio_actor/init.py). This raises an exception as PWM.GPIO does not like to create a new object attached to a pin that has already been assigned, and requires that the control be pressed a second time to switch the actor on.

The simple way to prevent this is to check whether the PWM object exists with if self.p is None: and only try create the PWM object if it doesn't already exist.