* Migrate `System::pipe(...)` calls to `System::map(...)`
* Migrate `EventReader::iter()` and `EventReader::into_iter()` calls to
`EventReader::read()`
* Migrate asset handling
* Generate `*.meta` files for assets
* Migrate a shader import
* Fix emissive materials double-applying their emissive strength
* Fix non-normalized bone weights resulting in incorrect vertex positions
* Set shadow filtering to `Hardware2x2` to mitigate increase in shader
compilation times
This PR adds the bones of a user-facing scene inspector.
### Work Done
To facilitate this work, the Bevy/frontend interface has been expanded to
accommodate two-way communications:
- The Bevy app can now dispatch JavaScript `CustomEvent`s via
`wasm::dispatch_to_js(...)`
- The frontend application can receive those events by listening for the given
event type on the `window` object
In its current state, the inspection system works by attaching the `Inspectable`
marker component to any entities which should be exposed to the user. A Bevy
system runs on `Update` to check for newly spawned or despawned entities with
that component, and emits events to notify the frontend. The frontend listens
for those events and updates its model of the scene accordingly, which is then
displayed with a simple tree view.
### Future Enhancements
There are many improvements that must be made to make this system actually
useful, but this PR is being expedited to focus on migrating to Bevy 0.12. A
shortlist of planned updates:
- Identify and expose the "type" of entity (e.g. lights, cameras, meshes,
skeletons, etc.) via a field on the `Inspectable` component
- Highlight the currently selected entity in the frontend hierarchy
- Ask the Bevy app to update the selection when the user selects an entry in the
hierarchy
- Add a separate UI panel to inspect and modify the selected entity's components
via the frontend
Danny McGee