Adjust MAX_LENGTH with BACK_ON_HOME

pos 0 take in account BACK_ON_HOME but this was not reported to
MAX_LENGTH so if BACK_ON_HOME has not null value MAX_LENGTH is over
sized.
Modify Clean Nozzle function in menu

Add temperature management in clean nozzle function from menu by adding
new event loop allowing key usage and cancelation function without
changing the current logic of main loop, cancelation screen is fully
customizable so it can be reused in others functions.
Now Clean Nozzle can be stopped at any steps of the action (or resume)
giving more control to end user.
Cancel function use Back key to be launched, then Left, Right, OK keys
to choose what to do.
Clean Nozzle keep extruder hot until end user decide action is done by
pushing OK key.
Switch SIMPLE_MENU to the New Menu System

I switched everything over to the new menu system:

- Load Filament
- Unload Filament
- Clean Extruder
- Clean Dripbox
Fix for UI_AUTORETURN_TO_MENU_AFTER

This part of the code is no longer needed with the New Menu System
Added Calibration via Menu (Auto Leveling)

Also cleaned up the Language Files, and removed isFilamentLoaded() which
never seemed to work for me.
Attempt to Fix Calibration via Menu

Not sure why, but for some reason the z-height is not being set in
eeprom. I'm trying to find a fix.
Add Sound management in quick menu

Allow to switch on/off sound for beep/M300 command
Fix for Calibration via Menu

I found the issue and fixed it. Calibration via Menu is working fine
now.
Better "Clean Driptray" Function

Moves the nozzle further to the left to allow for easier removal of the
drip tray.
Changed Z_PROBE_HEIGHT to 0.3

Makes filament stick to the bed better.
Modify Light On setting to be stored in eeprom

Store Light On/Off setting in eeprom, Warning need to flash eeprom with
setting, or load from configuration M502 then store M500 or from menu to
store setting for first time, if not ligh may be off until set manually
in menu
Fix Light On Setting Stored in EEPROM, and Others
Revert "due hangs fixed"

This reverts commit b206ee59a20e77d744ba67b9f08aed136737a0f9.
Disable Watchdog for now (until I can find a fix)
Save Sound / Powersaving setting to eeprom

Add: Save Sound / Powersaving setting to eeprom to avoid to set them at
each power on. If powersave time does not match preset values of 0, 1,
5, 15 or 30 min, value is used as it is but status only show powersave
ON
Fix : Move light setting to eeprom class instead of printer class
Save Sound / Powersavings - Store on change

Allows these settings to be saved to EEPROM on change.
Merge pull request #3 from drbogger/Testing

Merge testing branch into davinci branch