pass current document to views, so they work on this document, not with global pointers and MainWindow

use radio buttons instead of comboboxes for 2-choice-options; fix missing update on project load; add missing "document modified" after editing; refine UI

* introduce QtDesigner ui file for SimulationView
* move code spreaded over related UI classes to SimulationView
* remove these obsolete UI classes
* remove generic UI creation (SessionItem/-Model)

All of the above increases maintainability and eases understanding of the code base

As recommended by
https://google.github.io/styleguide/cppguide.html#The__define_Guard

Correct .h file header comments: "Declares" -> "Defines". Also remove include comment "inheriting from". This resolves #1550.