[TASK] some restructuring
[FEATURE] ElementWrapperTest::getWrappedElement
[TEST] ElementWrapper wrapped children tests
[BUGFIX] ElementWrapper::hasChildren

wrong return value for empty ObjectStorage
[TEST] ElementWrapper hideWrappedElement
[TEST] Page creation date
[TEST] Content getter setter
[FEATURE] pagetree recursive wrapping
[FEATURE] PageTree::firstLevelPages

with first implementation of filters and wrapped elements
[TASK] refactor pagetree with foreach element
[FEATURE] PageTree hideChildrenOfHidden
[FEATURE] PageTree::configuration
[FEATURE] configure hideChildrenOfHidden
[FEATURE] register a signal for filter initialization
[FEATURE] test for abstractFilter and modification for pagetree
[FEATURE] Filter hides not allowed elements
[TEST] exclude doktype filter

and refactoring for pagetree
[TEST] Doktype\ExcludeFilter filter
[TEST] Doktype\Only filter
[TEST] Page::setCreationDate