Fix renaming of classes in presence of generic signatures and nested classes.

[pietrobraione]

This is a possible fix for issue #298 that allows to rename a class and its nested classes in presence of generics. If for example we consider the following class:

package a.b;

public class C<W> {
  private class D<X> {
    private class E<Y> { }
  }

  D<Integer> d;
  D<Float>.E<Double> e;
  public static <Z> C<Z> make() { return new C<Z>(); }
}

the fix allows, e.g., to rename the class a.b.C to p.q.R and keep unchanged the names of the nested classes as follows:

ClassFile cf = new ClassFile(new DataInputStream(new ByteArrayInputStream(Files.readAllBytes(...))));
final HashMap<String, String> renames = new HashMap<>();
renames.put("a/b/C", "p/q/R");
renames.put("a/b/C$D", "p/q/R$D");
renames.put("a/b/C$D$E", "p/q/R$D$E");
cf.renameClass(renames);
cf.compact();
cf.write(new DataOutputStream(new FileOutputStream("...")));
//do this for C.class, C$D.class and C$D$E.class

I am not sure that this semantics complies with the meant one for Javassist.