Updates to support 5 extruders

Marlin/Configuration.h

Marlin/Configuration_adv.h

Marlin/configuration_store.cpp

Marlin/example_configurations/Cartesio/Configuration.h

Marlin/example_configurations/Cartesio/Configuration_adv.h

Marlin/example_configurations/Felix/Configuration.h

Marlin/example_configurations/Felix/Configuration_adv.h

Marlin/example_configurations/Felix/DUAL/Configuration.h

Marlin/example_configurations/Hephestos/Configuration.h

Marlin/example_configurations/Hephestos/Configuration_adv.h

Marlin/example_configurations/Hephestos_2/Configuration.h

...in/example_configurations/Hephestos_2/Configuration_adv.h

Marlin/example_configurations/K8200/Configuration.h

Marlin/example_configurations/K8200/Configuration_adv.h

Marlin/example_configurations/K8400/Configuration.h

Marlin/example_configurations/K8400/Configuration_adv.h

...in/example_configurations/K8400/Dual-head/Configuration.h

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

Marlin/example_configurations/RigidBot/Configuration.h

Marlin/example_configurations/RigidBot/Configuration_adv.h