[2.0.x] Extruder-Distinct Linear Advance K Factors

[SJ-Innovation]

Linear Advance is often used on Multi-Extruder setups where each extruder uses a different material. Obviously the material properties therefore differ so a different K factor will be required for each extruder.

This also allows the use of LinAdv on one extruder but entirely disabling on others, this is useful for hybrid direct-bowden drives where too high a K factor on the direct drive unit can ruin the print.

This PR adds individual K factors and their required setters on the LCD menus.

[SJ-Innovation]

Hi, I keep asking questions i know. Bear with. Sorry.

These formatting corrections you make, do you do them all by hand? Or do you have some form of auto-formatter? I feel awful for making you do such menial corrections should you do them by hand.

If you do use an autoformatter, which do you use? And what setup for it do you use?

Thanks,
Sam :)

[thinkyhead]

I do it all meticulously by hand, except things like stripping out trailing whitespace or locating tabs, where I will use global search (and replace).

[SJ-Innovation]

Fair enough, I'll make a concerted effort to minimise your correction load in future then!

[thinkyhead]

Appreciated! Just do your best imitation of the existing code style. For anything you might add there's almost always a precedent that can be followed.

[SJ-Innovation]

Will do, thank you for your patience.