Multiple Rows For Same Timeslots

[avery-chung]

For Course with multiple session choices in same timeslot, e.g. COMP4900, it may not be convenient to swap to the session "at the bottom".
Consider to show same timeslot sessions into one "course box" with session labelled "Multiple".
After dragging current "course box" onto it, show dialog box of session list for choosing, and do swap.