lift the inference engine up a level

src/ir.rs

@@ -12,10 +12,8 @@
 //! validating syntax, and then figuring out how to turn it into Cranelift
 //! and object code. After that point, however, this will be the module to
 //! come to for analysis and optimization work.
-mod ast;
+pub mod ast;
 mod eval;
 mod strings;
-mod type_infer;
 
 pub use ast::*;
-pub use type_infer::{TypeInferenceError, TypeInferenceResult, TypeInferenceWarning};