in all Configurations.

- Add “Level Bed” menu item for auto bed leveling
- Hide the option if homing has not been done yet
- Arrange the Prepare submenu more logically (?)
- Add documentation comments, some white-space
- Apply some coding standards here and there
- Move old encoder multiplier debug option to `ultralcd.cpp`

This addresses comments in #1956 and #1079. In particular, this is useful
when both endstops are stationary on a CoreXY system, and the Y axis needs
to be homed before the X so the flags are aligned.

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

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.

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

- Replace “Mendel” with “RepRap”

The line const bool Z_PROBE_ENDSTOP_INVERTING = false; // set to true to
invert the logic of the endstop is in the main configuration.h but
wasn't present in the example configuration.h's. Causes a compiling
error with Z Probe enabled. Just added it to all the configs. :)

- Sections in all `Configuration_adv.h`
- Recognize JAPANESE/WESTERN/CYRILLIC options
- Better capturing of comments for tooltips

- Addressing issue mentioned at #1699

Don’t set CUSTOM_M_CODE_SET_Z_PROBE_OFFSET if there’s no Z probe

make it unconditional
remove all definitions in the 'Configuration.h's
remove form 'Conditionals.h'

- `Conditionals.h` is included twice, setting LCD values the first time

- 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

Added option to set Travel Acceleration (non printing moves).
The M204 options was a non sense (S for printing moves and T for retract
moves).

It has been changed to:
P = Printing moves
R = Retract only (no X, Y, Z) moves
T = Travel (non
printing) moves

I will add this info o G-Code wiki in reprap.org. I also advise to put
this info in Marlin next version changelog.

commit 697ee2dc50

- Nonlinear auto bed leveling code (includes G29, G30, Z_RAISE_AFTER_PROBING). Cleaned it up to be a delta-specific AUTO_BED_LEVELING_GRID code path.
- Allen key z-probe deployment and retraction code. Cleaned it up and added safety checks.

- Moved sanity-checks to Marlin_main.cpp
- Applied to other configuration files
- Fixed formatting of ABL output
- Passing verbose level to probe_pt
- Miscellaneous cleanup
- Put CONFIG_STEPPERS_TOSHIBA into Configuration.h

Looks like INVERT_E3_DIR was missing in the configuration.h also as I
did a test compile with 4 extruders and Azteeg X3 Pro defined. So I also
added those lines too. Additional formatting to make the comments line
up better in that section.

I've insert the define and pointer entries for the Viki 2 and miniViki
from Panucatt in all of the example configs and main config. With these
additions and with pins done in the old single pin.h style...I was able
to get the display working fine save for needing to turn Delta Segments
per Second down. But that's a common graphics lcd issue being looked
into right now.

I need assistance in understanding how the new divided pins files fit
together because my previous attempts at trying to get it to work
appropriately didn't seem successful. This originally came from trying
to find out how to swap the XYZ Min and Max Endstop pins in the Azteeg
X3 Pro. It only comes with one set of connectors and they're Min
Endstops. My previous experience didn't turn out well trying to tell the
firmware to home to the Min Endstops so the best solution I found was to
swap the pins in the firmware. If I'm missing a conflict with a setup
other than delta please let me know, but it makes sense in my setup.

Here were a few changes that I had to make/add lines for the 4th hotend.
A compiling problem in the Temperature.cpp and missing lines in
configuration.h and configuration_adv.h. I added these lines in all of
the example configs too.