SPI TFT LCD on Uno R4 Minima

Sorry, this is outdated. I didn't have time yet to create a pull request.
The master library now supports the MCUFriend kind of shields, and SPI displays should also work with UNO R4. Added: I need to verify this, later today.
See also https://forum.arduino.cc/t/r4-tft-lcd-running-examples/1185495/6
-jz-