[2.0.x] Discard "continued" blocks on interrupted move

Update TEMP_BED_PIN in MIGHTYBOARD_REVE

[2.0.x] MULTIPLE_PROBING — Why stop at 2?

[2.0.x] Improved Core-compatible jerk code

[2.x] Address #8644

Removed missing include file

[2.0.x] Purge blocks on endstop/probe hit

[2.0.x] Cleanup, bugfixes, parity with 1.1.x

[2.0.x] Don't split first_move while homing or probing

While homing or probing it might be bad if the stop/trobe triggers during the first part and the second is still in the buffer.

Pin K7 number in fastio1280.h is 69, but it's also ADC15 pin. 
To get correct value from ADC reading it should be set as 15.

Addressing #8676

[2.0.x] Compilation errors with PIDTEMPBED only

* fix for #8669

* Update G28.cpp

Possibly more should be brought over? Discussion at #8471

Addressing https://github.com/MarlinFirmware/Marlin/pull/8575#discussion_r154536617

[2.0.x] Support for RAMPS Plus (3DYMY)

[2.0.x] SERIAL_XON_XOFF not supported on USB-native AVR devices

[2.0.x] Split first move to planner for better chaining

User could enable SERIAL_XON_XOFF on USB-native devices and it would not be enabled without warning, but M115 would report the capability as available.

[2.0.x] LPC1768 - add explanations in spi_pins.h

1) add explanations as to why software SPIs are selected

2) remove unused flag/option