language.h: update documentation for LANGUAGE_INCLUDE

@thinkyhead What do you think? I think there should be a warning like
this.

Minor wording correction.

Now ending in an endless loop.
Tidy up the output format.
We now get:
ERRORTEXT ", system stopped! Heater_ID: " HEATERID

Where ERRORTEXT can be:
"Heating failed"
"Thermal Runaway"
"MAXTEMP triggered"
"MINTEMP triggered"
and soon
"Thermal Jump"

HEATERID can be
0, 1, 2 ,3 , "bed"

This messages are always followed by the common:
"Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)"

- Use a global pointer for the current sanitized command
- Pre-sanitize the current command to bypass `N` and nullify `*`,
removing the need for handlers to bypass, ignore, or nullify these
parts, and reducing overhead for `code_seen`, etc.
- Pre-skip leading whitespace.
- Only look for G, M, T codes at the start of the command.
- Verify that G, M, T codes are followed by command codes.

Moved SDCARDDETECTINVERTED and SDSLOW to Conditionals.h.
Added U8GLIB_LM6059_AF to define display specific actions.
Added reminder to compile in u8glib

Name magic value 20 to MAX_OVERSHOOT_PID_AUTOTUNE

to make it better findable.

Have G92 set the nozzle position on Delta and SCARA

Rename of define to avoid confusion between the controller and the
display which had similar names.

Fixes for some code formatting changes and commenting out the
ADAFRUIT_ST7565 define that was left defined.

Added support for new display type

rework out_bits

Code style and a dangling "else"

Rename gCode to codenum as a consistency

Hide M117 with no LCD

Add gcode_line_error to reduce code size

Rename process_commands to process_next_command

Tweak to fan kick routine

NO_TIMEOUTS and ADVANCED_OK off by default

Allow lsDive to recurse with minimal stack usage

add plan buffer remaining for 'P' and block buffer remaining 'B'

Display unknown XYZ on the LCD as "---"

Use MSG_OK in M105