Improve main_*.py

Modify modules/common/data.py
    rename get_json() -> load_json()
    add dump_json()

Modify main_*.py
    use modules/common/data.py
    rename variable data_config -> config

Delete print modules
    delete modules/course/print_course_dept.py
    delete modules/course/print_course_id.py
    delete modules/score/print_score.py