[2.0.x] Add a README.h file for Arduino IDE users

get rid of twi.h

move to board files

Setup FolgerTech i3-2020 Configuration files as a reference platform for
32-Bit work.

Also fix MAX7219 debug lights on 32-bit platforms.

2.0.x - MPC4451 I2C support

[2.0.x] Move FILAMENT_RUNOUT_SENSOR to a feature

[2.0.x] Serial double echo fix

[2.0.x] Different NEOPIXEL types

Same as #7728 but for 2.0.x,
Lot of cleanup and remove references in whole code to other "LED files" than leds.h. Now will be much easier to add next drivers/libraries. e.g. FastLED. But bad news, currently FastLED is suporting only RGB devices (no RGBW)

[2.0.x] Remove legacy ADVANCE feature

[2.0.x] Allow UBL G29 and G26 to build without a probe

[2.0.x] Use segmented moves when moving axis from LCD

[2.0.x] Add support for 4 new LCDs

[2.0.x] Addressing #7896

Compiler error, added char c variable

Fix double character sent when TX buffer size is 0 on mega2560

[2.0.x] Update LPC persistent store to initialize eeprom.dat with FF

* Auto-enable DISABLE_REDUCED_ACCURACY_WARNING if HOME_AFTER_DEACTIVATE enabled

If HOME_AFTER_DEACTIVATE, there is no need to warn on LCD since printer will home prior to starting print.  Saves 60 bytes PROGMEM on AVR with U8g panel.

* Reduce lines used

* Reduce lines used

[2.0.x] Apply fixes for DUE

Alternative to #7882. If F_CPU is greater than 1000 it can be evenly divided by 8. Over 10000, 16; over 100000, 32; over 1 million, 64; etc.

[2.0.x] Addressing #7612

[2.0.x] Resolve USE_CONTROLLER_FAN compile errors

Add to controllerfan.cpp:
#include "../module/stepper_indirection.h"
#include "../module/temperature.h"

Change "extruder" to HOTEND in sanity error messages

This change initialize any data in eeprom.dat beyond the current file size to FF.
That way if eeprom.dat is deleted and created again, it doesn't take the old values or random ones, but rather starts with FF in all positions as a real brand new or erased eeprom.dat
Currently if you delete eeprom.dat and restart the board, the new file is created in the same sector with the same content, since FAT does not actually delete the data, just marks the sector as free. I tested by deleting the file, and then rebooting the board, and checking the file content.
The change can be tested in the same way, deleting, rebooting the board, and then the new content should be all FF.

If an eeprom file already exist with data on it, but smaller than E2END, it will be padded with FF on first access, so it will not have random or old content appended.

[2.0.x] Fixing ANET encoder pulses

[2.0.x] Fix sd file list display bug

Derived from #7873

[2.0.x] Apply G33 updates

[2.0.x] Add UTF-8 mapper for Slovak language

Adapted from #7865

Based on #7862, #7846 by @rmoravcik

As pointed out in #7692 by @totalitarian

* test only

test

* Fixed RAMPS FD V1 pins.h file

* Fix typo

When the buffer is empty index_write == index_read, but they needed constrained by buffer_mask