Refactor and cleanup editor dialogs
Collection task:
- Refactor id vs. class in editor dialogs (which are now overlaying each other ->duplicate id problem)
- Improve selectors in js code, which (1) need to adress classes and (2) should only work on own modal
(from redmine: issue id 547, created on 2018-01-22tgradl, closed on 2018-01-22)
- Relations:
- relates #536 (closed)