Extra infos for advanced users

Some feature requests.

• New entry below the average grade displays on main window for passing rate (percentage of students who passed)
• In exam options window, a possibility to toggle between bonus points included in calculation and bonus points not included into calculation.
  • Include this in the save file
• Another entry in the exam menu tab named “Additional statistics”, which opens a window like with the options window. Make it copy, pastable:
  • Number of all students who took the exam
  • Number of students who did not attend: students who are listed in the rwthonline sheet but did not take the exam
  • Number of students who are not in the rwth online file listed but took the exam