added asignment 3

works apart from an error with the session duration management
Improved assignment 3

everything works except refreshing 1st page
final version assignment 3
assignment 4
Final version assignment 4

Added user input checking

theres a known bug with the refreshing of questions causing a recheck of
the previous question (resulting in more than possible 'correct'answers)

The fix I could think of is to either A keep track of if an answer was
answered correctly via an array or to exit the session upon refresh
(checking another page and then coming back to the quiz does not trigger
this bug)