change test framework to use files for in and out (s-exp)

test/cases/module_def/module_class.tst

@@ -0,0 +1,11 @@
+module Foo
+  class Bar
+    funcall(3 , var)
+  end
+end
+-- -- --
+s(:list,  [s(:module,  "Foo",  [s(:class,  "Bar",  nil,  [s(:call, 
+  s(:name,  "funcall"), 
+  s(:arguments, 
+    s(:int,  3), 
+    s(:name,  "var")))])])])