May models menu

created a may models menu in MID context menu.
Made some new listeners, made minor changes to old listeners for slightly different functionality.
We try to use Require-Bundle for this type of things (i.e. Required Plug-ins rather than Imported Packages), but the main problem here is that this makes Z3 mandatory in any MMINT installation (the "Core" projects shouldn't depend on the availability of additional things like a specific solver). I'll comment again once I understand why you need Z3 here.