Made Treemodel interactive + made ScenarioList changable without reloading

So this should fix Bug #2942 (Treeitem / Treemodel reload without model reset). I had to change the treemodel for it. The ScenarioListView should now be changable without loosing the collapsed state. The were some buggy behaviours while creating this, but i think i caught them all. Please have a look at it i might have missed something though.

Added 7 commits:

• eabec751...c25c827b - 5 commits from branch master
• 339236d4 - Merge branch 'master' into ScenarioManagerTreeViewFixes
• fa9461a3 - Fixed behaviour for equally named scenarios in different packages

it should work now with scenarios which have the same name

Status changed to merged

mentioned in commit 9a93cc66

Mentioned in commit 9a93cc66