rustboot: Don't use walk to traverse statements in type.ml; fixes redundant checking, improves diagnostics. Also report untyped slots.

Switch module-internal calls (i.e. all user code) to fastcall. Still returning via explicit outptr. Activate glue works by accident.

Move phi-node generation into a helper that measures the liveness of each incoming edge. Factorial test now succeeds.

rustc: Add an annotation to function and type items so that the typechecker can store types with them

Teach rustc about const tag value, begin work on trans_copy_ty, make uint's to_str routine less clever and thereby resist overflow.