implement slotClear to clear a single prop visualisation

Could we add a small doc, what is actually cleared?

added 1 commit

• 0ea3c4e5 - Add comments for add/clear slots.

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@moebius done.

I have to say that at some point, a better API that allows being more specific about which property is worked on would be very useful. For now, I just mirrored the existing slotVisualizeProperty slot.

mentioned in commit b6ed8e92

merged