Added Lockable Warning (kinda)

Added: If you try to invoke a function which has no executable executors (locked executors are not executable), you will receive a warning which also reminds you of the lockable feature. That's just a help for developers who forget about the locking/unlocking.
Added Default setParent() Call in Accessor Utilities

Added: The function executors created by the property accessor factories now check if the incoming object/element is a ChildFeatureHolder. If that's the case, they call the setParent() method of the child feature holder to set or remove the parent holder correctly.
getExecutors() in FunctionDefinition

Added: A class which implements function definition now has to provide a getExecutors() method for getting the registered function executors.
Fixed Doubled FunctionExecutionException Message Bug

Fixed: When an exception occurres during the invokation of a function executor, the resulting FunctionExecutorException will no longer "merge" with the originally thrown exception.
Function Parameters

Added: The function framework now provides argument checks. You can define which parameters are supported by a function. On invokation, the function will check if the parameters and arguments match. You can also define varargs by using XX[] as parameter (e.g. String[] for String...).