Firmware retraction: Fix and extend zhop feature

[fbeauKmi]

Reopen the pull request #211. There was to much changes from the previous PR
@pdscomp @richfelker

This PR fix issue #204.
New firmware_retraction vs old version:

• The code use gcode_move transform instead of G0/G1 overwrites. the zhop is applied as an offset, it does not affect gcode position (solve an issue with pause/resume). It opens the code to wipes features.
• add clear_zhop_on_z_moves parameter . Allow to clear zhop if a move in z is requested when toolhead is retracted
• CLEAR_RETRACTION doesn't reset parameters to default. RESET_RETRACTION is added to do that.
• add zhop_state status, independent of retract_state
• no automatic reset of retract_state and parameters on events (home, print_start, print_end). Zhop is reset ONLY on G11/home/stepper off.

Checklist

• pr title makes sense
• squashed to 1 commit
• added a test case if possible
• if new feature, added to the readme
• ci is happy and green

[pdscomp]

@fbeauKmi
Just wanted to report I've been running my main printer off this branch exclusively since early November, and have not noticed any buggy behavior. My settings are:

• Firmware retraction enabled in OrcaSlicer
• Default retraction set to 0.6 with no Z-Hop in printer.cfg
• Each "Material settings" (filament profile) configured with some variation of the following (or commented out if no change from default):
  • Filament start G-code:
    M118 Overriding default Z-Hop, setting to 0.2
SET_RETRACTION z_hop_height=0.2
GET_RETRACTION
    or for PETG:
    M118 Overriding default retraction, setting to 1.2 and Z-Hop, setting to 0.4
SET_RETRACTION retract_length=1.2 z_hop_height=0.4
GET_RETRACTION
  • Filament end G-code:
    M118 Clearing retraction override settings, going back to Klipper defaults from config
CLEAR_RETRACTION
GET_RETRACTION
• This allows me to view the settings at the start of each print and then check that they are back to default at the end of each print, and I haven't noticed any discrepancies doing spot checks on tens of prints.
• My other use case is to use this to tweak retraction and z_hop_height during a print in order to come up with a value that minimizes stringing and improves finish quality of the layer being printed
  • I've used SET_RETRACTION and GET_RETRACTION extensively during prints to tweak both retract_length and z_hop_height during a print with no ill effects / no unintended offsets being added to the nozzle
  • Examples are increasing retract_length from 0.8 to 1.0, 1.2, 1.4, etc. and z_hop_height from off (0) to 0.2 to 0.4 to 0.8 and turning off again while observing how the printer is printing, and running GET_RETRACTION to make sure my settings were captured
• Overall I'm extremely happy with the performance of this latest MR, and prior to this had been running off of the PR211 branch exclusively
• The updates to documentation are clear and make sense to me!

Based on the above testing, I would heartily recommend this for merge, I don't believe this change introduces any new bugs and being able to easily tweak and reset my retraction and z_hop during a print is an EXTREMELY useful feature. I think the updates to RESET_RETRACTION vs. CLEAR_RETRACTION are also perfect for most people's use cases.

Cheers and thank you for the hard work on this!

Paul