Cleanup filter() functions

[peters-axon]

Currently there exists no clear concept of filter functions.

• A filter() function should do the same filtering for a collection of objects as the manipulateCriteriaFactory() function does during the query.
• Before returning, a filter() function should call the super.filter() function.
• A filter() function should not be static.
• A filter() function should return a modifieable list as result.