Remove commented code (closes #98)

Basic but useful implementation.

Removes basic commented code like

````csharp
// var i = 10;
````

multiple commented code lines:
````csharp
            // this comment will be preserved
            // if (something)
            // {
            //   DoStuff();
            // }
````

some nonvalid code, but...

````csharp
            // this comment will be preserved
            // class Fee
            class Foo
            {
            }
````