libws2812 doesn't work with some production variations

[AndyLindsay]

Discussion notes:

Initially:

• Determine timing that gives the most room for manufacturing variations.
• Establish that timing.
• Test (in progress).
• Update BP demo and production when tests pass.

Next:

• Decide whether the 1.7 us approx delay between successive lights in the chain will be okay for all situations.
• If yes, integrate and test updated driver for timing and flexibility.

If a custom driver is needed:
In Simple Libraries, cog 0 already has space reserved for inline terminal communication, so we probably won't replace the driver with one that's inline. It'll likely be a CogC or PASM library, depending on the author's preference.