Speed up Sprite rotation on an ESP32
Update utf8 serial decoder to handle illegal format strings
Remove need for D0_USED_FOR_xx (issue #271)
Clean up setup files
Correct various comment typos
Also added ability to push 1bpp bitmaps to a Sprite to support rendering
images on an EPaper screen.
Floyd-Steinberg dithering and basic graphics example added as first
ePaper demo.