HardwareSerial has been tested on Uart0 (debug header) and Uart3 (i2c connector)
Software Serial has been tested to work bi-directionally at 9600 and 115200
using pins 6 and 63 on J5, and unidirectionally (write only) at 250000.
The code used to test was Teemuatlut's tmc2208 patch, and a few small changes to main used to echo recieved chars back to a host pc.

Uses PWM1 to directly control pins 4, 6 & 11 (servo 0, 1 & 3) and PWM1
generated interrupts to control other pins.

Interupt control of the servo pins had too much jitter so switched all
that we could to PWM1 direct control.  The PWM1 direct control pins have
less than 1 microsecond pulse width jitter while the interrupt
controlled ones can have 20+ microseconds of jitter.

Also added insurance to the servo code in the "disable servo after move"
section.

* LCD_UBL_memory_slot_corrections

Changed the memory slot edit function to work with the
`settings.calc_num_meshes()`

* Add a little more safety margin...

* More corrections

Error handling when the EEPROM is not available.

* UBL_correction

* RGB Map function

This reverts commit 2dfa6ca72a.

Revert "Base HAL SPI Changes"

This reverts commit 2afc521b8b.

Revert "Initial HAL SPI API"

This reverts commit 58f7ffe09a.

Re-ARM has been tested.  AVR has not been tested.

1) moved all cpu specific items to files in the low level HAL directory
for that CPU (pinDebug_Re-ARM.h & pinsDebug_AVR_8_bit.h

2) added pinsDebug.h to the top level directory

3) modified HAL_pinsDebug.h to select the correct support file for the
selected CPU

4) Patched sanitycheck to stop throwing false errors.  A long term
solution will be done

5) misc changes & bug fixes
arduino.cpp - included macros.h to fix a missing definition
pinmap_re-arm.h - removed a duplicated line.
pinmapping.h - changed from "ENABLED" to "defined" to fix a compile
error

======================================================================

split SanityCheck up, improve pinsDebug system

======================================================================

switch to latest pins_RAMPS_RE_ARM.h

Fixes Arduino IDE builds for 8-bit AVR,
misc: Adafruit NeoPixel currently incompatible with Teensy 3.5-6, blacklisted

Add macros.h to allow Enabled macro, also need to reference include files directly

Implement AVR Platform