Changed the text boxes in QuestionsUI to comboBox. Now the user can only
select questions from a drop down list.

Added tooltips to the group generation comboBox in the SystemUI class,
now the user can get a better explination of each option available.

The GUI runs as it should, although a NullPointerException is thrown
each time the groups are generated, though it does not stop the program
from working.
Merge branch 'master' of https://github.com/Torraville93/CS3716.git