Adding PWM2 and RWD2

Adding two commands, PWM2 and RWD2 that allow additional settings in PWM. The gap can now be set so that it different between a one and zero, and a waveform between bytes can be added.

I also increased the comms buffer size from 128 to 256, as it was too small to hold the bit string for my application.

Note that this patch is not particularly well tested as I don't have any tags.