* Multi-nozzle selective duplication
* Use a bit-mask, reduce stepper_indirection.h size
* Tweak the multi-nozzle duplication description
* Use 'S' as a bool in M605
* Add HAS_DUPLICATION_MODE conditional
* Remove '_MODE' from the option name
* M605 in the style of Stacker M280
* Also include direct mask style (P)