Merge Slow SD Handling #2848

Marlin/cardreader.cpp

Marlin/example_configurations/Felix/Configuration.h

Marlin/example_configurations/Felix/Configuration_DUAL.h

Marlin/example_configurations/Hephestos/Configuration.h

Marlin/example_configurations/K8200/Configuration.h

...le_configurations/RepRapWorld/Megatronics/Configuration.h

Marlin/example_configurations/RigidBot/Configuration.h

Marlin/example_configurations/RigidBot/Configuration_adv.h

Marlin/example_configurations/SCARA/Configuration.h

Marlin/example_configurations/TAZ4/Configuration.h

Marlin/example_configurations/WITBOX/Configuration.h

...in/example_configurations/adafruit/ST7565/Configuration.h

Marlin/example_configurations/delta/biv2.5/Configuration.h

Marlin/example_configurations/delta/generic/Configuration.h

.../example_configurations/delta/kossel_mini/Configuration.h

...n/example_configurations/delta/kossel_pro/Configuration.h

Marlin/example_configurations/makibox/Configuration.h

Marlin/example_configurations/tvrrug/Round2/Configuration.h

Marlin/pins_RIGIDBOARD.h

Marlin/ultralcd.cpp