Small patch

Probably should made these a fews days ago but oh well

Addition:

• Added a new challenge suggested by pink_zazel (mentionned in the credit)
• Added a vending machine and a notebook finder in front of the cafeteria

Changes:

• Removed some bookshelves in the library to prevent teachers from getting stuck on them

Bugfix:

• Fixed Thavel getting stuck with the other teachers
• Fixed collision in the library
• Fixed not getting some achivements and challenge not becoming beaten when you, infact, have beaten them