Add M701/M702 Filament Load/Unload, M603

.travis.yml

Marlin/Configuration_adv.h

Marlin/src/Marlin.cpp

Marlin/src/Marlin.h

Marlin/src/core/language.h

Marlin/src/feature/pause.cpp

Marlin/src/feature/pause.h

Marlin/src/gcode/control/M17_M18_M84.cpp

Marlin/src/gcode/feature/pause/M600.cpp

Marlin/src/gcode/feature/pause/M603.cpp

Marlin/src/gcode/feature/snmm/M702.cpp

Marlin/src/gcode/gcode.cpp

Marlin/src/gcode/gcode.h

Marlin/src/inc/SanityCheck.h

Marlin/src/lcd/ultralcd.cpp

Marlin/src/lcd/ultralcd.h

Marlin/src/lcd/ultralcd_impl_DOGM.h

Marlin/src/lcd/ultralcd_impl_HD44780.h

Marlin/src/module/configuration_store.cpp