Based on #8685

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.

Addressing #8676

Addressing #8662

Conflicts:
	Marlin/boards.h

When using RELOC_WORKAROUND library needs to be linked explicitly, otherwise
eeprom functions are not available.

Thanks to @rfjakob for finding the crucial hint to solve this issue.

* SERIAL_XON_XOFF not supported on USB-native AVR devices

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.

This reverts commit 0eef0ff0de, reversing
changes made to d8582b7506.

Address #8573, #8595

-Report SERIAL_XON_XOFF in Extended Capabilites M115 report for hosts
-Remove outdated 256 size limitation from comments on RX_BUFFER_SIZE defines
config updates
-Update error checking conditions

* Add default configuration files for the Wanhao Duplicator 6.

* Update Configuration.h

G26 uses logic that looks like:
```
ex = _GET_MESH_X(i + 1) - (SIZE_OF_INTERSECTION_CIRCLES - (SIZE_OF_CROSSHAIRS));
```
The Bi-Linear macros need parenthesis to work correctly.