- added "<Class> object filter" and "<Class> object mixin" - use explicit "(object|class)-(mixin|filter)" relations in ::xotcl::relation - removed "-per-object" from all user-level relation commands (::xotcl::relation has still "-per-object"), but it is not needed anymore - register slots "object-mixin" and "object-filter" for conveniance to allow object-filter and object-mixins via configuration via object parameter