Host Keepalive configurable timeout with 2s default

Fix bug which can cause an infinite M109 loop

Update language_da.h

Update language_da.h

Optimized Italian strings to fit in 16 character display

de-language additions

Since residency_start_ms is -1 when entering the heatup while loop whilst the hotend temp is close to the target them already then it may not escape.

Hence "Start the TEMP_RESIDENCY_TIME timer when we reach target temp for the first time."

M155 and M156, a generic TWI/I2C interface for Marlin

Additional debug leveling output

This may fix a subtle bug caused by doing `G29` more than once without
`G28` between.

No LCD Move for unhomed Delta/SCARA

No casting needed for SERIAL_ECHOPAIR

Report the probe position in G30

Update pt_PT translation

M109: Protect against EXTRUDE_MINTEMP expansion

Print job timer rework

Fix FILAMENT_WIDTH_SENSOR measurement

Consolidate REPRAPWORLD_KEYPAD, disallow moves for unhomed Delta/SCARA

Rc bug fix

Corrected:
MSG_KILLED
MSG_NO_MOVE
MSG_STOPPED
MSG_PRINT_ABORTED
MSG_ON
MSG_OFF

Added translation mentioned in issue #3351:
Homing would be best tranlated homing, or "Kører til udgangsposition".

#define MSG_SET_HOME_OFFSETS
#define MSG_LEVEL_BED_HOMING
#define MSG_LEVEL_BED_WAITING 
#define MSG_LEVEL_BED_DONE
#define MSG_LEVEL_BED_CANCEL 
#define MSG_HOME_OFFSETS_APPLIED

Optimised Ducth messages to fit in 16 Char display Update language_nl.h

Optimised all added messages to fit within 16 Characters

Only measure and store filament width when E is going forward.

rebased my fork with RCBugFix release in order to push language_nl.h

Update Readme.fonts about Kana

Update to language_it.h

I think that that sentence has been completed its part. 
Because Kana fonts were revised by me the other day(PR #3289), who am a native Japanese.

And for @AnHardt,
I'd like to take this opportunity to express one's heartfelt gratitude as a far eastern person,
about you has been maintaining the resource of Japanese despite you are a far western person.

Rc bug fix