Formatting
Remove ClassID property and constructor from class Student
Rename StudentManager.cs to Main.cs
Formatting
Refactor Manager's method names

- AddStudentToClass -> AddStudentClass
- RemoveStudentFromClass -> RemoveStudentClass
- ChangeClass -> ChangeStudentClass
Finish the previous renaming commits
Add solution policy (indentation, standard header, etc.)
Remove GetStudentFromID and GetClassFromID
Implement utility methods of Manager
Forget binary files
Ignore StudentManager/bin
Remove Class' constructor and implements IComparable, IEquatable
Implement IComparable and IEquatable for Student
Make ClassStudentRel a readonly property
Various changes in Manager.cs

- Make AllClass private
- create enumerable properties for AllStudents and AllClasses
- AddStudentClass now checks if the class has been registered
- Add FindStudentById method
Update adhoc tests in Main
Typo AllClass -> AllClasses
Private variable name should be camelCase not _PascalCase

Also make AllClasses immutable and add classRoomSlots
Some more name refactoring
Add struct Room and struct TimeSlot