Remove SF_ARC_FIX from G5 (Cubic B-spline).
SF_ARC_FIX is a fix for G2/G3 (arcs) where Skeinforge always produced relative instead of absolute coordinates for the endpoint of an arc.
It's very unlikely this is also a problem with Cubic B-splines. More likely is copying from the G2/G3 code.
No compromises for the manage_heater(). manage_heater() will return immediately when there is nothing to do, but needs a constant detaT to work proper.
Calling idle() only every 200ms results in a display update every ~2 seconds - that should be enough.
For the other functionalities in idle() and manage_inactivity() 200ms is a lot but hopefully works.
Additional follow-up the PR #3631(Encapsulate Stepper, Planner, Endstops in singleton classes)
・Change from abort_on_endstop_hit to stepper.abort_on_endstop_hit in endstop.cpp, Marlin_main.cpp, and ultralcd.cpp
・Add include path to cardreader.h and temperature.h in endstop.cpp(for CardReader class and disable_all_heaters())
It fix compilation error when ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED and SDSUPPORT are enabled.
・Change from digipot_current() to stepper.digipot_current() in Marlin_main.cpp
・Change from digitalPotWrite() to stepper.digitalPotWrite() in Marlin_main.cpp
It fix compilation errors when HAS_DIGIPOTSS is enabled.
・Change from microstep_mode() to stepper.microstep_mode() in Marlin_main.cpp
・Change attribute of microstep_mode() from private to public in stepper.h
・Change from microstep_readings() to stepper.microstep_readings() in Marlin_main.cpp
・Change from microstep_ms() to stepper.microstep_ms() in Marlin_main.
It fix compilation errors when HAS_MICROSTEPS is enabled.
Follow-up the PR #3631(Encapsulate Stepper, Planner, Endstops in singleton classes)
plan_bed_level_matrix -> planner.bed_level_matrix in multi extruders section of Marlin_main.cpp
It probably fix the Issue #3658(plan_bed_level_matrix not declarate).
movesplanned() -> planner.movesplanned() in ADVANCED_OK section of Marlin_main.cpp
It fix compilation error when ADVANCED_OK is enabled
