various list-loading adaptions
NEW: module_system | class_db -> flushing the database-cache no longer flushes the table-cache, too. this may be triggered by a special method of class_db since only relevant for package installations / updates
UPDATE: module_postacomment | recorddeleted listener -> refactored the post-loading in order to generate less queries on object deletions
UPDATE: module_navigation | portal generation -> updated some internal data structures to speed up the tree generation
UPDATE: module_pages | pageelement -> the internal row-cache is now merged into the orm init row cache