- Use `setTargetedHotend` in `M200`, as with other commands that use
`T` for the extruder
- Synthesize the "invalid extruder" message, obviating several long
strings

language.h: update documentation for LANGUAGE_INCLUDE

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

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)"

This reverts the changes done to the error message for line number mismatches done in commit d43cc2dd5f

- Also move audio feedback into the command
- Added shorthand for `lcd_buzz` availability

This makes `M421` more amenable for irregular matrices

language.h: update documentation for LANGUAGE_INCLUDE
language.h: URL für K8200 github repository

Edited the European part of 'ISO10646_CN.fon' to match the existing fonts.
Added Chinese font to make_fonts.bat
Created 'dogm_font_data_ISO10646_CN.h'
Added Chinese to 'language.h'
Added 'language_cn.h' with some minor edits.
Added Chinese font in 'language_en.h' to not fall back to European font.
Added cn to 'Configuration.h'
Changed WIDTH to LCD_PIXEL_WIDTH and HEIGHT to LCD_PIXEL_HEIGHT to have more descriptive names.

In 'dogm_lcd_implementation.h'
Added Chinese Font
Made 1 pixel more room for the larger Chinese font on the status line.
Changed geometry of the 'select bar' by one pixel.
Changed the way the position for values and postcars are set.

With these changes the output of `M503 S0` is all you need to restore
the EEPROM. Building on this it is straightforward to save and restore
the EEPROM state using the SD card or external GCode file.

- Added `M145` to set “heatup states” for the LCD menu
- Added `M420` to toggle Mesh Bed Leveling
- Added `M421` to set a single Mesh coordinate
- Extended `Config_PrintSettings` with added M codes
- Cleaned up some comments here and there

- Add `M111` as a standard option to set the debug level
- Implement `DEBUG_ECHO` in `process_commands`
- Other debug levels (e.g., `DEBUG_DRYRUN`) need more work

- Replace “Mendel” with “RepRap”

+ update in documentation

Thank you @Nprod!

The automatic versioning system extracts a
build version number from the SCM system

That versioning information is written to the file
_Version.h, a file that is NOT preserved in the SCM.

If such a file will be present,
we include it here to utilize the parameters
that are defined therein.

Catch unlikely but possible error and head crash when using
Z_PROBE_REPEATABILITY_TEST

- Patched up for most included configurations

Z_DUAL_ENDSTOPS is a feature to enable the use of 2 endstops for both Z
steppers - Let's call them Z stepper and Z2 stepper.
That way the machine is capable to align the bed during home, since both
Z steppers are homed.
There is also an implementation of M666 (software endstops adjustment)
to this feature.
After Z homing, this adjustment is applied to just one of the steppers
in order to align the bed.
One just need to home the Z axis and measure the distance difference
between both Z axis and apply the math: Z adjust = Z - Z2.
If the Z stepper axis is closer to the bed, the measure Z > Z2 (yes, it
is.. think about it) and the Z adjust would be positive.
Play a little bit with small adjustments (0.5mm) and check the
behaviour.
The M119 (endstops report) will start reporting the Z2 Endstop as well.

- Add `Conditionals.h` with calculated configuration values
- Add `SanityCheck.h` with checks for configuration errors
- Remove equivalent code from all configurations
- Move error checks from some sources to `SanityCheck.h` also
- Fix initialization of count_direction in stepper.cpp

Automatic selection was to unflexible.

Updated documentation

Updated language files to new logic and documentation.

Updated bdf2u8g.exe

Include of language_en.h now behind national language.

All "#define MSG_STR_*" now surrounded by #ifndef and #endif.

+ May decrease the workload for feature developers. They may omit to
update all the language files but "language_en.h". When loading _en
first, all new features give some display, but the new in English.

- May throw some additional warnings about redefinition during compile.

Select DOGM-displays automaticly.
Give hint where to find charsets.
Add '²' and '³' characters.

This reverts commit 4d5b0e2037.