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
Added M112
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
Added estop handling
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Test and refactor
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
More coverity fixes
Merge pull request #851 from DanNixon/estop

Implemented M112
Add M112 description to Marlin_main
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Configuration.h, pins.h: Add MOTHERBOARD 84 for Teensy++2.0