Simplified version of hookshot's forwardInvocation

hookshot-forwardInvocation.mm

- (void)forwardInvocation:(NSInvocation *)inv {
    Class targetClass = [self class];
    SEL selector = inv.selector;

    runCallbacks(beforeBlocks, self, targetClass, selector);
    @try {
        IMP imp = method_getImplementation(class_getInstanceMethod(targetClass, selector));
        // This is a private method and must not make it's way to production code!!
        [inv invokeUsingIMP:imp];
    } @finally {
        runCallbacks(afterBlocks, self, targetClass, selector);
    }
}