Fix bug in hotend_heater_ctrl.cfg that allowed probing while nozzle is hot

[austinrdennis]

Fixes #301.

This is inelegant, but this prevents the nozzle from touching the bed surface when too hot in all cases. Let me know if you think of something better or want to tweak it, but at least it can be fixed for now. I'm guessing at the dwell time of 5 min in a worst case scenario. It could probably be less, but I only have a Revo and that cools down quick so I assume other hotness have considerably more thermal mass than mine.

[austinrdennis]

Fixes the issue #301 now that I fully understand why that was happening. My testing shows the issue to be corrected, ready for merge and issue closeout.

Now I could be misunderstanding the intention behind the TEMPERATURE_WAIT command call in M109. Maybe the problem is the way ACTIVATE_PROBE is using M109 is not correct for tap. Perhaps a MINIMUM and MAXIMUM need to be specified to prevent edge cases like this one, but then what's the difference between this and base M109 at that point?

It is possible to use a BambooLab hotend with Voron TAP. I don't think I'm wrong for setting "fix_heaters_temperature_settle" to true, but I'm using it in an unanticipated configuration perhaps.

I thought I'd take a shot at a fix, feel free to leave me corrections until we get something that works. I can't seem to revert the previous commits for some reason and if that becomes a problem, I can just delete this fork and redo another PR when we have it the way you want.

[Frix-x]

You are right, but please look at my answer (#301 (comment)) in the original issue :)

[austinrdennis]

The latest commit is my best attempt at implementing a solution that both fixes the bug and provides the functionality for low thermal inertia heaters. It works as intended in my testing, but I'm just one person with one machine so there may be edge cases I haven't thought of.

It's possible to stall the printer indefinitely (put it in a "busy" status) as this is currently implemented: If a M109/M190 command is issued with a S value that is less than the ambient air temperature in the room the printer is in, the printer will simply freeze up waiting for temperature to stabilize below room temp. I think we can agree that scenario is unlikely to happen in normal use and is pretty much harmless if it does occur. I think worst case is some cooked filament is a nozzle left for a long period in this state, but nothing more.

Let me know what you think and how I could improve on it! Thanks for taking time out of your day to go back and forth with me.

[Frix-x]

Ok, I think this is now good to go for me :)
Thank you for you work and help in debugging this feature! I'll merge it for the next version of Klippain!