add missing global
validate_row(): use hard/soft/dryrun api, too; numeric update: check for existence
init $debug if no debug button is shown
debug_button(): alternative view if no dropdown available
sql_save_group(): handle new fields status, professor_groups_id
activate cache mechamism
use new affiliations_groups_ids field to avoid many sql calls
use new affiliations_groups_ids field to avoid many sql calls
implement debug menu in pp