fill toolbar with actions, not with buttons

Closes #103

See merge request !225

Select items after inserting to sample designer

Closes #7

See merge request !224

Refactor UI creation of SimulationView

See merge request !220

this fixes #103 (GUI: "More..." button in JobWidget is not working)

explanation for changes: filling toolbars with buttons breaks the "more"-button functionality, therefore use the already existing actions to fill the toolbar

this fixes #7 (GUI: After inserting multiple items to the sample editor they should all be selected)

Prepare Beam for refactoring of distribution handling

See merge request !222

libParam: start active reading ...

See merge request !221

* 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

Refactor model: distribution items

See merge request !219

rm IComponent

See merge request !218

Some minor renaming of functions of the distribution items to be consistent with other function names

Refactor SimulationOptionsItem for strong typed methods

See merge request !217