- `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

- 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.

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.

This define is not used.

- Fixed issue when BAL area probing is shorter than it should be for
grid probing
- Warning when BAL activated with Delta Kinematics
- Fix XY_TRAVEL_SPEED when homing Z axis

For legacy boards it’s better if this option is disabled.

For legacy boards it’s better if this option is disabled.

Save above configs in eeprom
fix docs in createTemperatureLookupMarlin.py
add missing azteegX3pro digipot settings in delta example config

Signed-off-by: Joseivaldo Benito Junior <jrbenito@benito.qsl.br>

Also added a couple of missed merge lines in homeaxis() from previous
commit.

add more delta defaults
on delta make second home even slower

Dual x-carriage designs offer some substantial improvements for dual
extruder printing.

M109 S180 waits only when heating.
M109 R180 also waits when cooling.

Diffed and merged, preserving my updates

Also refactor extruder auto fan logic to simplify further and now only
check every 2.5 seconds

This change allows fan outputs to automatically turn on/off when the
associated nozzle temperature of an extruder is above/below a threshold
temperature.
Multiple extruders can be assigned to the same pin in which case the fan
will turn on when any selected extruder is above the threshold.
It also makes the M42 command compatible with the M106/M107 command.
The majority of the logic in this change will be evaluated by the
compiler at build time (i.e, low code space requirements).

[default off for now]
syntax: M600  X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal]

if enabled, after a M600, the printer will retract by E, lift by Z, move to XY, retract even more filament.
Oh, and it will display "remove filament" and beep like crazy.

You are then supposed to insert a new filament (other color, e.g.) and click the display to continue.
After having the nozzle cleaned manually, aided by the disabled e-steppers.
After clicking, the printer will then go back the whole shebang, and continue printing with a fancy new color.

Add a feature to run the cooling fan at full speed for a small period
(default 100ms) when first starting the fan.  Some fans wont reliably
start spinning at low power, and many fans have issue with the PWM at
low power.  However, once the fan starts spinning it can reliably be
set to a wide range of PWM values.