New Features:
ScheduleDay.lessons is now sorted based on start_time
ScheduleWeek now has entries for all weekdays

Fixes:
Removed a println used for debugging

Other:
Improved documentation

commits:
6aa6c7e - Changed from HeapMap to binary search
1f0badb - removed unwanted println
2da3126 - Changed ScheduleDay to use a BinaryHeap
e428288 - documented the Occasion struct
799ed28 - formating
e461632 - function for getting a specific ScheduleWeek day
2c53f8d - typo
f164bab - Implemented From<&Occasion> for Lesson
193dc92 - Added saturday and sunday to ScheduleWeek
1a466c2 - Started work on massive test refactor