Add a configuration option for inverting the PWM signals to the GUI.

[ShuzzDE]

Many simple FET driver circuits require low-active driving.
For example, simply adding a small NPN and two resistors per channel to your original schematic would allow the IRLZ44N FETs to switch much higher currents than currently possible with only 3.3V of gate voltage.

This would be useful for people building their own hardware.

[patrickjahns]

The details for this feature would best be implemented at the RGBWWLed Library level
https://github.com/patrickjahns/RGBWWLed/blob/master/RGBWWLedOutput.h
https://github.com/patrickjahns/RGBWWLed/blob/master/RGBWWLedOutput.cpp

The Configuration can the be easily done via setting a flag during instantiation in the firmware