Migrated to Bevy main, now that spawning PR is in.

feat: Add CoreRadio.

refactor: Checkbox API now consistent with other widgets.

refactor: `Cond` and `For` now use consistent calling conventions.

refactor: Renamed `IndirectSpawnableList` to `SpawnableListGen`.

refactor: Renamed `MutateDyn` to `Calc`.

Worked out how to sync text styles with dyn_children.

....and I left in an import that should have been deleted.

refactor: Migrated all uses of UiTemplate to Template.

refactor: Partial migration from UiTemplate to Template.

feat: `Invoke` for templates.

Experimenting with templates that implement `SpawnableList`.

Migrated Switch.

Deleted CreateForEach.

Initial implementation of For::each().