Make all exceptions extend std::exception

Change-Id: I6d7afc12c282eec7642aef44a2d8d5b77a9efd19
Make the menu application independent

Change-Id: Ie1681f367eb5a064b1e60d52d935ba4708bb72a1
Make the menu more beautiful

Change-Id: I7d21f109e1965d6692f1eeecaeb0d74fb931e87a
Use shared_ptr instead of regular pointers

Change-Id: I504fe2d9a2bc188bec9798f2eecfbc487eb985e9
Implement CreateStudent menu entry

Change-Id: I9223bc01d09711ae794ffce3e539eb3370b388c0
Clean up the includes

Change-Id: Idae1a31c54af740b5f1475c2040881e6945e9f95
Implement AverageMark menu entry

Change-Id: Ibd70b35f0bc6eb0aab23fa2d6d6537d1af9e2301
Implement << operator

Change-Id: I637d154153282b8106b33ed1fe8c35ddb4619dfc
Implement << operator

Change-Id: I9f819d98ddebeb8dd4cb099a6ac5cfb374881728
Implement AgeGroup entry which prints
all students between 18 and 26 years old

Change-Id: Ifbfb5c8f09b906f0b05eec4f38964bdcef5a2fdc