Class hirerarchy almost finished
problem to solve: virtual base related error
buggy Student list serialization
add delegate to edit Date and Sex(enum)
change class name -> StudentTableDelegate
open and save Student list to file
don't need to subclass QTableWidget, use directly
dont need to subclass QTableView, delete StudentTableWidget
CommonTableModel fail, Q_OBJECTS doesn't support template class
copy StudentTableModel to teacher, postgraduate, TA
working version
working set, will remove QSortFilterProxyModel in next commit