Merge https://github.com/ErikZalm/Marlin into Marlin_v1
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' into Marlin_v1_Mendel90

Conflicts:
	Marlin/cardreader.cpp
	Marlin/pins.h
Restore X and Y Home offset of 1mm to centre bed.