don't support changing world or worldobject types
fix import_world_signature
remove add/delete nodetype api functions

not used, buggy. We might want to offer CRUD-functionality for native-modules at some point, but this is currently not in the scope
drive-by-fix: typo, function stubs
fix gatefunctions init
change new_nodenet to auto-instantiate nodenet

also, change import nodenet and import world to not overwrite existing worlds. that's what merge is for
consistency: change monitor api to return uid, not data