Demonstrates how to set the colour of a WS2812B to blue using PWM, and the use of multiple sequences along with their own config. This required an API change.
I had introduced a small bug in my last PR where I assigned the sequence before stopping the PWM. I now stop the PWM before doing that now.
Also, corrected a math comment.
Sequences are now passed in via the start method to avoid having to stop the PWM and restart it. Sequences continue to be constrained with the same lifetime of the Pwm object itself. The pwm_sequence example has been extended to illustrate multiple sequences being passed around.
