Tried to solve #11, but stopped because:
a) SimpleVerifier of ASM has gaps: Analyzer.merge(..) of two interfaces
that have a common superinterface will not work (marked as TODO there).
b) There are some classloaders that won't provide the class files as
resource inputstream (NoStackClassLoader for RMI). 
b) is not an issue, but a) should work. I feel the algorithm should work
properly for ASM, then I can include it. 

For now: ExtendedCheckClassAdapter exists, but isn't used.

However work on #11 improved #10 further: now also interface assignments
are properly checked when injecting fields or arguments into methods.