* Core: hot reload components from installed apworld
* address PR reviews
`Launcher` widget members default to `None` so they can be defined in `build`
`Launcher._refresh_components` is not wrapped
loaded world goes into `world_sources` so we can check if it's already loaded.
(`WorldSource` can be ordered now without trying to compare `None` and `float`)
(don't load empty directories so we don't detect them as worlds)
* clarify that the installation is successful
Doug Hoskisson