Compile with debug information
Add NULL to ExtraArgument class
Add missing hashCode/equals
Add join(Object...)
Fix missing finalization
Load CtClass really from the provided bytecode
Add instrumentation across more methods

It is possible to start the measuring in one method and collect the
result (i.e. duration) in another one. A separate test is provided
in the CallbackInstrumentationTest class. Refactoring is needed.