Fix order of REPL stack types given to inference

The REPL stack is right-to-left, but type inference expected
stack types left-to-right.  A `[Type Scalar]` named 'stack'
or 'stackTypes' would be understood as right-to-left, so
this change makes the type a `Vector (Type Scalar)` (meaning
left-to-right) instead.
Merge pull request #91 from strager/fix-repl-type-inference

Fix order of REPL stack types given to inference