match Java's schizophrenic concept of inner class access modifiers

An inner class has two sets of modifier flags: one is declared in the
usual place in the class file and the other is part of the
InnerClasses attribute.  Not only is that redundant, but they can
contradict, and the VM can't just pick one and roll with it.  Instead,
Class.getModifiers must return the InnerClasses version, whereas
reflection must check the top-level version.  So even if
Class.getModifiers says the class is protected, it might still be
public for the purpose of reflection depending on what the
InnerClasses attribute says.  Crazy?  Yes.

Fixes #190.