Implement animation root motion deltas (#84)

Implements root motion and adds a dash attack.

Reviewed-on: #84
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/manifest.rs

@@ -62,12 +62,19 @@ pub struct FighterManifest {
     pub icon: TextureReference,
     pub attributes: FighterAttributes,
     pub camera: FighterCameraProfile,
+    /// Bone whose model-space translation drives gameplay root motion.
+    #[serde(default = "default_root_motion_bone")]
+    pub root_motion_bone: String,
     pub animations: HashMap<AnimKind, String>,
     pub attack_scripts: HashMap<AttackKind, String>,
     pub hurtboxes: Vec<FighterHurtbox>,
     pub ecb_bones: Vec<String>,
 }
 
+fn default_root_motion_bone() -> String {
+    "root".into()
+}
+
 #[derive(Resource)]
 pub struct FighterManifestAssets(pub Vec<Handle<FighterManifest>>);