Kit-Selection should be session-specific

I use multiple sessions to distinguish different kits. So I'd have one session "qtdev" (where I have loaded for example the webengine project from dev branch), one session "qt5.7" (where I have loaded for example the webengine project from 5.7 branch) etc.

I also have a browser project, which I have loaded in multiple sessions (to debug into different versions of webengine).

The problem now is that I set the browser project to kit "dev" in the qtdev session. Then I set it to kit "5.7" in qt5.7 session and when I switch back to qtdev session, the it is still set to kit 5.7. Sometimes, this causes confusion, because I switch the session, don't mind the kit and end up debugging into the wrong webengine version.

The kit-selection should be session-dependent, in my opinion. Changes in one session should not have side-effects in other sessions.