conlang: Unify binding operations!

This breaks out the pattern matching/unification algorithm from cl-interpret/interpret.rs to cl-interpret/pattern.rs

TODO: pattern destructuring in const, static :^)

compiler/cl-interpret/src/lib.rs

@@ -25,6 +25,8 @@ pub mod function;
 
 pub mod builtin;
 
+pub mod pattern;
+
 pub mod env;
 
 pub mod error;