no user will home to 0 with a max endstopp

and removed some tabs.

Centralised beep code to lcd_buzz().
From gcode_M300() and lcd_quick_feedback().

Enforced max. duration for M300 to 5 seconds.

Corrected description in 'Configuration.h'

LCD_FEEDBACK_FREQUENCY_HZ 0 gives now a silent delay of
LCD_FEEDBACK_FREQUENCY_DURATION_MS.

Corrected wrong order of parameters.

Introduced in commit 697ee2dc and later spread to other files.

I.e., when acceleration * steps per mm > 2,000,000.
This was done by changing MultiU24X24toH16 to take a 32b bit operand.
Removed the claim that stepper.cpp uses the Leib algorithm.

Ensure the probe offset will always be included when homing Z.

example_configurations\K8200\Configuration.h:
* merge upstream changes from default Configuration.h manually
* add some machine specific comments

Example Configuration for K8200 : comments/URL/readme

example_configurations\K8200\Configuration.h:
* add machine specific header
* change STRING_URL to K8200 fork (@thinkyhead: What do you think?)

example_configurations\K8200\readme.md:
* updated documentation
* added URLs and links

Example Configuration for K8200 : comments/URL/readme

example_configurations\K8200\Configuration.h:
* add machine specific header
* change STRING_URL to K8200 fork (@thinkyhead: What do you think?)

example_configurations\K8200\readme.md:
* updated documentation
* added URLs and links

example_configurations\K8200\Configuration.h:
* merge upstream changes from default Configuration.h manually
* add some machine specific comments

- Potentially addressing #1911

Copied from jcrocholl's contributions to the OpenBeamUSA Marlin fork

- Change some `previous_` time vars to `next_` so an add only happens
at intervals
- Fix `HEATER_0_USES_MAX6675` polling too frequently, or not at all

lcdDrawUpdate = 2 helped a lot!

- Prevent `Z_SAFE_HOMING` from homing Z twice in some cases
- Allow `G28` with XYZ values of 0 to explicitly set the position
- Don’t add `home_offset` when setting XYZ explicitly in `G28`
- Add `code_has_value` function to check for the presence of a numeric
value (could just test for space or nul to allow other types of values)

- MENU_ITEM causes lcd_quick_feedback to be called, so only those calls
to `lcd_goto_menu` outside of the `MENU_ITEM` macro need to set the
`feedback` flag when calling `lcd_goto_menu`.

- Replace “Mendel” with “RepRap”

- It’s inline here, but could be a macro and duplicated for
`planner.cpp`