Added Diagram Statistics and Window

Under the View Tab one can now click the Diagram Statistics button to open a window which shows some rudementary statistics about the currently openend diagram

Issue ticket number and category

Provide reference ticket id and choose ticket type.

[ ] Feature
[ ] BugFix

This branch could be deleted after the changes were pulled [YES/NO]

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Checklist:

[ ] I have performed a self-review of my code
[ ] I have commented my code, particularly in hard-to-understand areas
[ ] I performed tests that cover the acceptance criteria
[ ] I documented my work in the ticket system
[ ] The ticket was labeled with testing. Test were performed and no bugs were found
[ ] XMF needs to be updated

Release Notes

Please provide a one-liner that summarizes the added feature or the fixed bug for the description of the next release.

xmf-xmodeler / MosaicFX