Merge pull request #1 from ErikZalm/Marlin_v1

merge
Activate LiquidTWI2 device detection and space-pad LCD status line.
Merge https://github.com/ErikZalm/Marlin into Marlin_v1
Prevent SD card insertion from causing a hang when using LiquidTWI2 device detection
Merge branch 'lcd_detected' of https://github.com/whosawhatsis/Marlin into Marlin_v1
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Allow use of either SD Card slot when LCD Panel is configured.
Preference is for Controller SD slot before LCD Panel slot when both are occupied.
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Support for Gen3 Monolithic electronics

Techzone Monotronics support, ignoring the tip manager and using fan connector as on Sprinter FW
TODO: Add support for tipmanager
Merge https://github.com/ErikZalm/Marlin into Marlin_v1
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
restore Branch from Backup

sorry for that
fixed wrong compiler-option
Fix lcd itostr3() to handle negative numbers
optimised some math-code
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Update pins.h

Leapfrog board added to the pin list