collection of minor bugs V2

There are more minor bugs:

• Run correction (single) crashes in a variety of cases (including #64 (closed))
• Validate vertex validation for circular windows in FZK-Haus IBPSA (IFC)
• Rename correction (single) to single correction
• Replace Save-Button with Export Button (?)
• Remove Clear button
• Validation Settings in Transformation viewer without function (remove for now)
• Main / Start window: about button, add proper text (Project Name, Contact, Contributors, License info)
• for the problematic beam in the FZK Haus: add a warning in the syntax checks if the RelatedBuildingElement is missing and mark it in the treeview --> additionally add the warning to the individual report
• #65 (closed)
• #63 (closed)
• #43 (another discussion needed here probably)