OCaml's variableWrapper() wasn't calling emit_action_code() for
in/out typemaps, which meant that %allowexception was being ignored.
In addition, remove all comments in the typemaps in Lib/ocaml. In the
case of the allowexcept test, one of the typemap comments caused
compilation to fail because it became nested within another comment
in an %exception block.
Re-enable the allowexcept test.
Add allowexcept_runme.ml.
