No "addMethod" for abstract methods with no body

[Sheimyn]

Hi there,

So I noticed you implemented support for interfaces, but you forgot to add a method in ClassFile.scala that adds a method with no code attribute. I locally wrote a method that handles this, called addMethodHead. Maybe you can implement it (or some variation of it) in your source code. The following picture shows the method I added:

Have a good one!