Added SD card storage for smooth fonts with ESP32
ESP32 will use PSRAM (if available and enabled) to hold smooth font
metrics
Improve performance of ESP32 Sprite shared functions
Add basic ST7789 driver option
Latent bug fixes for pin mask
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
Touch reliability improved by using pressure and double sampling. Added
Adafruit compatible Button class. Added touchscreen on/off and keypad
examples.