[orx-gui] Invoke onChange in Parameter Path

[hamoid]

It's the only parameter type that does not trigger change events.

Without this change changes to @PathParameter variables can't be detected in gui.onChange.

[hamoid]

I see now that my code is incomplete. Change events are not triggered when assigning a new value to the annotated variable.

[hamoid]

I found this demo https://github.com/openrndr/orx/tree/master/orx-jvm/orx-gui#demopath01 which shows how to persist a PathParameter.

This is enough for what I need, but there's an difference between how IntParameter and PathParameter or TextParameter behaves:

With IntParameter I can do settings.num = 5 and it triggers the gui.onChange { } listener. This does not happen if I do settings.t = "hi" or settings.imagePath = "demo-data/images/image-001.png". There's no events.valueChanged triggered in those cases.

Update:

I investigated further and find different behaviors in https://github.com/openrndr/orx/tree/master/orx-jvm/orx-panel/src/main/kotlin/org/openrndr/panel/elements

I think the only element that implements a setter that triggers valueChanged is
https://github.com/openrndr/orx/blob/master/orx-jvm/orx-panel/src/main/kotlin/org/openrndr/panel/elements/Slider.kt#L49

The other elements I looked into do not seem to implement such a setter.

[hamoid]

After recent changes to orx, I see that annotations like @TextParameter, @ColorParameter and others DO trigger onChange events 👍

If this should happen with @ParameterPath this PR can be merged, or closed otherwise.