Use lcd_bootscreen for both

Printrboard RevF cleanup

-Update Arduino IDE extension descriptions
-Set default motor currents if not defined in Configuration_adv.h
-Support for MINIPANEL LCD
-Support for choosing internal or panel SD

LCD for Melzi support

Expose DISABLE_M503 option as a test option

UBL radar map corrections

Add configuration for Infitary M508 (i3 clone)

Based on Infitary's own firmware settings.

intermittent AT90USB & G26 compile problem (proposal)

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also an issue with ubl_motion.cpp

Add a sanity check for DELTA_AUTO_CALIBRATION

Fix LETTER_OFF in gcode.h (make LETTTER_OFF return values that match param indices range)

Correct has_value() when FASTER_GCODE_PARSER is enabled

Also corrected compile issue when DEBUG_GCODE_PARSER and
AUTO_BED_LEVELING_UBL are both enabled.

Add ANET A6 example configuration

Add A (action) and E (echo) parameters to M118

UBL Map Cleanup and LCD display

M118 echo to serial

Allows the user to send text to the serial console in order to
communicate with a host - sending debuging information or action
commands, for example.  Text must begin with '//' and this is added if
it is not already present at the beginning of the string.

Followups for I2C_POSITION_ENCODERS

Use parser.seenval, add shorthand functions

Initial support for the Průša MK2 Multiplexer