* Add palette encoder
(cherry picked from commit c30692ee75b8a2e3aaf4d7d5b809c267f9066aed)
* Add full resolution Mandelbrot as example for palette encoding
* Switch to 2 symbols per word, this is performance neutral on the encode, but saves memory bandwidth
(cherry picked from commit 70834bfa1953a29d95e0d0f5ae16c86d2feb7242)
* Marginally faster palette encode
* Up to 256 colour palettes
(cherry picked from commit 86e0e5d7dd11020d01f167b8cad571391de56aee)
* Apply parity alternation to palette and other full res case
(cherry picked from commit e9971155ff08977275612e4d22d37f0f416ef13e)
* Use 256 colour palette, generate on both cores
* Clear up magic numbers
(cherry picked from commit 6180d210e59f25c7c4b4855920acdaa973447228)
* Use PICO_DEFAULT_LED_PIN
(cherry picked from commit 383c6eb4b6ea79b617d785e3736ea744746f57af)
Mike Bell