v0.1.8.1 fix

· Fixed the bug of students being addicted to vacation and unwilling to return to school.

· Fixed the bug that caused the game to freeze due to new students being unable to access the class schedule.

· Corrected the logic regarding student vacations.(Currently, the default start of school is on Monday, which means that if you set the academic year cycle to 5 or 6 days, students will attend five full days of classes before the weekend, and new students will be welcomed on Sunday. If you set the academic year cycle to 7 days, students will get a full 7-day long vacation, and so on.)

· Add an "auto pause" setting.

· Add some shortcuts to control the camera; now, in addition to the mouse, you can also move and zoom the camera using W/A/S/D and Z/X.