Add return to NOT_BUSY for M105
Replace WAIT_FOR_USER with PAUSED_FOR_USER

Add Travis test for FILAMENTCHANGEENABLE

Fix a SNAFU that should have been caught in #3012

Addressing #2773

Alternative fix to #3149

Addressing issue #2767

If Marlin is blocking the serial input or command queue for any length
of time (for example more than 2 seconds), it needs to send a message
to serial out to inform the host that it is busy. Marlin should only
send these messages out when busy, and preferably not when trying to
print formatted output.

follow-up the commit d56c6af24e

fixes MarlinFirmware/Marlin#3144 and MarlinFirmware/Marlin#3083

lcd_erase_line() is called with argument, but the argument is ignored by lcd_erase_line().

If comparison between signed char(-128 ~ +127) and DIR_NAME_DELETED(uint8_t const 0XE5, it's +229),
it makes incorrect result.

Addition to #3140

diagonal_rod hadn't been used anywhere.

Extend stack_overflow_protection for lcd_move_e() and _lcd_level_bed() with
a refined method of 3050.

follow-up the commit 7326d63ce0
update Configration_adv.h of Hephestos2
delete unnecessary spaces

Addressing #2879. The M115 report should display `MACHINE_UUID` but it
always displays `UUID`.

Addressing #3085. If the target_temperature is set directly it never invokes or disables the timer set in `start_watching_heater`, so after _stopping a print_ or turning off _all heaters_ you could get a “Heating failed” error.