rename ClassCompiler to MomComplier

ended up not even using the class, it just came from there
It actually compiles methods, and it turns out is the point where builtin comes into the picture as it's boot process also returns method compilers

test/vool/test_class_statement.rb

@@ -11,7 +11,7 @@ module Vool
     end
 
     def test_return_class
-      assert_equal Mom::ClassCompiler , @ret.class
+      assert_equal Mom::MomCompiler , @ret.class
     end
     def test_has_compilers
       assert_equal Risc::MethodCompiler , @ret.method_compilers.first.class