Merge pull request #6519 from thinkyhead/rc_cleanups_2

Marlin/Configuration_adv.h

Marlin/G26_Mesh_Validation_Tool.cpp

Marlin/Marlin_main.cpp

Marlin/configuration_store.cpp

Marlin/enum.h

Marlin/language_en.h

Marlin/language_fr.h

Marlin/least_squares_fit.cpp

Marlin/pins_RAMBO.h

Marlin/platformio.ini

Marlin/ubl.cpp

Marlin/ubl.h

Marlin/ubl_G29.cpp

Marlin/ubl_motion.cpp

Marlin/ultralcd.cpp