Bevy 0.19

[AndreRoelofs]

Hey,

Thanks for creating such a cool project, you helped me solve a challenging issue super nicely!

I did the 0.19 migration, as specified below:

1. Remove Resource derivations from Props according to the migration guide.
2. Make the original Props a component only.
3. Create GlobalProps newtype for Props that derives Resource and implements Deref for transparent access to Props.
4. Add simple gitignore
5. Run cargo fmt --all
6. Updated docs to reflect the changes
7. Add simple tests for props to confirm baseline functionality
8. Add a test to check if the code works with the newly released bsn! macro as per some Discord discussion
9. Bump version to 3.0.0 and update related docs.

I am not usually for using Deref on newtypes but I feel like it fits very nicely in this particular case.

The naming for the newtypes was chosen to loosely follow Bevy's example namely

UiDebugOverlay is split into GlobalUiDebugOverlay (resource) and UiDebugOverlay (component)

[goulvenclech]

Same port on our side (we consume this through bevy_bae) with one difference: Props stays the Component, and only GlobalProps is added. Either works for us, though consumers such as bevy_bae build unchanged against ours, but need a mechanical Props → EntityProps swap against this one.

[AndreRoelofs]

I agree, that is a better solution, made the change.