intermediate Medium/Resource refactoring

docs/reference/uri.md

@@ -0,0 +1,11 @@
+Quick thoughts and ideals:
+
+- Schemes are compositional, "wrapping" super contexts: `c+b+a://a/b/c`
+- The scheme communicates the target type (above is `c`)
+- URIs can be arbitrarily relative so long as they're resolved in the right contexts.
+  Above, `c+b://b/c` can be resolved in the context of `a://a`
+- URIs are resolved by unwrapping schemes and resolving in to out
+- URL params can apply only to the target type (this is the most consistent and probably
+  not too restrictive)
+- Trajectories from one scheme to another can be inferred from the type hierarchy; there
+  may be many