BVH animation loading / retargeting (#25)

This PR adds support for BVH animation files, with a custom animation
player and retargeting solution for our Blender Rigify-based skeletal
meshes.

---------

Co-authored-by: Brooks Palin <brookspalin710@gmail.com>

studio/src/bvh/error.rs

@@ -0,0 +1,38 @@
+use core::fmt;
+
+use anyhow::anyhow;
+use bevy::prelude::Deref;
+
+#[derive(Debug, Deref)]
+pub struct Error(pub anyhow::Error);
+
+impl From<anyhow::Error> for Error {
+    fn from(value: anyhow::Error) -> Self {
+        Self(value)
+    }
+}
+
+pub trait Anyhow<T> {
+    fn anyhow(self) -> anyhow::Result<T>;
+}
+
+impl<T, E> Anyhow<T> for Result<T, E>
+where
+    E: std::error::Error,
+{
+    fn anyhow(self) -> anyhow::Result<T> {
+        self.map_err(|err| anyhow!("{err}"))
+    }
+}
+
+impl std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        self.0.source()
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", **self)
+    }
+}