Add and use `ems.update` to react to attr-changes
Record changes for electric entities, too

* Call `do_callbacks` of changes unconditionally
Early update of entites started
Fix last_cid update problem for copy changes
Allow dotted names for `Alias_Property`
Improve text of `Name_Clash`
Continue implementing Uniqueness predicates
Bug fixing for `keep_zombies` handling
Finish implementing Uniqueness predicates
Show single appointment in PDF_Plan_Month.one_day