Confirm deletions before doing them, in treemodel

[aufuss]

Referring to this (2019) https://github.com/jven/studyopenings/issues/2 This solution only warns you of permanent deletion if you press tie x on the repository list.

If you have a repository opened and you click to the first move, then on the trashcan, the complete repository gets deleted without warning or possibility to undo.

I lost a huge repository on the stafford gambit, plz fix.