animation player (#4375)

# Objective

- Add a basic animation player
  - Single track
  - Not generic, can only animate `Transform`s
  - With plenty of possible optimisations available
  - Close-ish to bevyengine/rfcs#49
- https://discord.com/channels/691052431525675048/774027865020039209/958820063148929064

## Solution

- Can play animations
  - looping or not
- Can pause animations
- Can seek in animation
- Can alter speed of animation
- I also removed the previous gltf animation example

https://user-images.githubusercontent.com/8672791/161051887-e79283f0-9803-448a-93d0-5f7a62acb02d.mp4

CREDITS.md

@@ -21,5 +21,6 @@
 * Ground tile from [Kenney's Tower Defense Kit](https://www.kenney.nl/assets/tower-defense-kit) (CC0 1.0 Universal)
 * Game icons from [Kenney's Game Icons](https://www.kenney.nl/assets/game-icons) (CC0 1.0 Universal)
 * Space ships from [Kenny's Simple Space Kit](https://www.kenney.nl/assets/simple-space) (CC0 1.0 Universal)
-* glTF animated triangle from [glTF Sample Models](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/AnimatedTriangle) (CC0 1.0 Universal)
-* glTF box animated from [glTF Sample Models](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/BoxAnimated) ([CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) - by [Cesium](https://cesium.com))
+* glTF animated fox from [glTF Sample Models](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Fox)
+  * Low poly fox [by PixelMannen](https://opengameart.org/content/fox-and-shiba) (CC0 1.0 Universal)
+  * Rigging and animation [by @tomkranis on Sketchfab](https://sketchfab.com/models/371dea88d7e04a76af5763f2a36866bc) ([CC-BY 4.0](https://creativecommons.org/licenses/by/4.0/))

Cargo.toml

@@ -17,6 +17,7 @@ members = ["crates/*", "examples/ios", "tools/ci", "errors"]
 
 [features]
 default = [
+  "animation",
   "bevy_audio",
   "bevy_gilrs",
   "bevy_winit",
@@ -43,6 +44,7 @@ render = [
 ]
 
 # Optional bevy crates
+bevy_animation = ["bevy_internal/bevy_animation"]
 bevy_audio = ["bevy_internal/bevy_audio"]
 bevy_core_pipeline = ["bevy_internal/bevy_core_pipeline"]
 bevy_dynamic_plugin = ["bevy_internal/bevy_dynamic_plugin"]
@@ -98,6 +100,9 @@ bevy_ci_testing = ["bevy_internal/bevy_ci_testing"]
 # Enable the "debug asset server" for hot reloading internal assets
 debug_asset_server = ["bevy_internal/debug_asset_server"]
 
+# Enable animation support, and glTF animation loading
+animation = ["bevy_internal/animation"]
+
 [dependencies]
 bevy_dylib = { path = "crates/bevy_dylib", version = "0.7.0-dev", default-features = false, optional = true }
 bevy_internal = { path = "crates/bevy_internal", version = "0.7.0-dev", default-features = false }
@@ -183,10 +188,6 @@ path = "examples/3d/lighting.rs"
 name = "load_gltf"
 path = "examples/3d/load_gltf.rs"
 
-[[example]]
-name = "manual_gltf_animation_player"
-path = "examples/3d/manual_gltf_animation_player.rs"
-
 [[example]]
 name = "many_cubes"
 path = "examples/3d/many_cubes.rs"
@@ -236,6 +237,10 @@ name = "wireframe"
 path = "examples/3d/wireframe.rs"
 
 # Animation
+[[example]]
+name = "animated_fox"
+path = "examples/animation/animated_fox.rs"
+
 [[example]]
 name = "custom_skinned_mesh"
 path = "examples/animation/custom_skinned_mesh.rs"