[OCaml] Add a typecheck typemap for SWIGTYPE

This fixes many of the remaining warnings in the OCaml test suite.

Add multiple runtime tests.

Examples/test-suite/ocaml/template_default_arg_runme.ml

@@ -0,0 +1,52 @@
+open Swig
+open Template_default_arg
+
+let _ =
+  let helloInt = new_Hello_int '() and enumArg = _hi '() in
+  assert (helloInt -> foo (enumArg) = C_void);
+  assert (helloInt -> foo () = C_void);
+
+  let x = new_X_int '() in
+  assert (x -> meth (20.0, 200) as int = 200);
+  assert (x -> meth (20) as int = 20);
+  assert (x -> meth () as int = 0);
+
+  let x = new_Y_unsigned '() in
+  let args = C_list [ C_double 20.0 ; C_uint 200l ] in
+  assert (x -> meth (args) as int = 200);
+  let args = C_uint 20l in
+  assert (x -> meth (args) as int = 20);
+  assert (x -> meth () as int = 0);
+
+  let x = new_X_longlong '() in
+  assert (x -> meth (20.0) as int = 0);
+  let x = new_X_longlong '(20.0) in
+  assert (x -> meth (20.0) as int = 0);
+  let args = C_list [ C_double 20.0 ; C_int64 200L ] in
+  let x = new_X_longlong '(args) in
+  assert (x -> meth (20.0) as int = 0);
+
+  let x = new_X_int '() in
+  assert (x -> meth (20.0) as int = 0);
+  let x = new_X_int '(20.0) in
+  assert (x -> meth (20.0) as int = 0);
+  let x = new_X_int '(20.0, 200) in
+  assert (x -> meth (20.0) as int = 0);
+
+  let arg = new_Foo_int '() in
+  assert (_ott '(arg) as int = 30);
+  assert (_ott '() as int = 10);
+  assert (_ott '(1) as int = 10);
+  assert (_ott '(1, 1) as int = 10);
+  assert (_ott '("hi") as int = 20);
+  assert (_ott '("hi", 1) as int = 20);
+  assert (_ott '("hi", 1, 1) as int = 20);
+
+  let arg = new_Hello_int '() in
+  assert (_ottstring '(arg, "hi") as int = 40);
+  assert (_ottstring '(arg) as int = 40);
+  assert (_ottint '(arg, 1) as int = 50);
+  assert (_ottint '(arg) as int = 50);
+  assert (_ott '(arg, 1.0) as int = 60);
+  assert (_ott '(arg) as int = 60);
+;;