* Encapsulate common LCD code in a singleton
* Depend more UBL code on UBL_DEVEL_DEBUGGING
  - Since most users don't need the debugging on at all times, this helps reduce the default build size for UBL by over 2K, a little closer to fitting on 128K boards.

* Apply #pragma once in headers
* Adjust some thermistors formatting
* Misc cleanup and formatting

Implement AVR Platform

Replace all fastDigitalRead/Write() with READ/WRITE()

Define SCK_PIN, MISO_PIN, MOSI_PIN in pins.h if not already defined in the pins_*.h files.

Remove these conditional pin definitions from the pin-files. They are now always defined.

Define separate sets of SPI-pins for AT90USB with and without Teensy support in fastio.h.
Likely this was the main reason for all that confusion about the AT90USB-SPI pins.

Following up on #3231

Keep "astyled" reformatting

at least the lcd independent part from Marlin_main.cpp.