Porting the panel driver to an ESP32

From Good Display's Arduino sample to a PlatformIO project, and an adapter board of my own.

Good Display's sample drove the panel from an Arduino board. Moving it to an ESP32 meant a PlatformIO project, the driver as a library, and a new pin map: busy, reset, data or command, and chip select on ESP32 pins, with SPI on its defaults.

In the same weeks the e-paper adapter board went into EasyEDA as a clone of Good Display's DESPI-C73, so the panel can plug into a board I drew rather than a module on the bench. The frame is still compiled into the firmware; fetching it from the renderer is the next step.