[2.0.x] LIN_ADVANCE v1.5

[thinkyhead]

Based on #9700 by @Sebastianv650

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Cleanup, squash and rebase of development branch, see #9379.

Changes to v1.0:

• K is now a meaningful value with the unit [mm of filament compression needed per 1mm/s extrusion speed] or [mm/mm/s].
• Load inside stepper ISR reduced as no calculations are needed there any more. Instead, the extruder runs at a fixed speed offset during pressure adjustment. Therefore this version runs faster.
• LIN_ADVANCE now respects hardware limitations set in Configuration.h, namely extruder jerk. If the pressure corrections would need faster adjustments than allowed by extruder jerk limit, the acceleration for this print move is limited to a value which allows to use extruder jerk speed as the upper limit.
• The pressure adjustment moves doesn't lead to a rattling extruder as it was in v1.0 as the extruder is now running at a smooth speed instead of jerking between multiples of extruder print speed.
• This smooth extruder operation and respecting of jerk limits ensures no extruder steps are skipped.

Keep in mind that:

• High K values (soft filament, bowden printers) will lead to print acceleration reduction. This is unavoidable to keep extruder speed in allowed ranges. You can't expect it's possible to draw a great piece of art with a cooked noodle - there is a reason why the handle of a brush is made from wood.

Todo, required in short term:

• Update Marlin documentation

[tcm0116]

This change to use F_CPU instead of HAL_STEPPER_TIMER_RATE breaks things on 32 bit systems. Specifically, the deceleration phase of motion is significantly slower than it should be. Reverting back to the use of HAL_STEPPER_TIMER_RATE alleviates the issue.

You might also want to look at the use of F_CPU a few lines down as well.

[thinkyhead]

Oops, that was a foolish oversight from using paste and not re-checking. I patched it this morning, and the line below.

[eyal0]

Hi. Is there a conversion from old K value to new K value that I could use?

I need it for this issue where my users are giving really large M900 K values to the printer. I don't want to support the old way so I'd like to just find some math that converts between them.

An approximation would be fine, too!