Alternative single port pinout keeping I2C available and multi panel support finished

Signed-off-by: ScruffR <scruff.r@sbg.at>

This is not cleaned up and some parts (e.g. fillScreen) are work in progress.

The logic if a given color for `fillScreen()` is `memset`able is still wrong - an overload for an enum of possible bytes would make sense and maybe some inline asm would be possible for other colors.