Improve support for year long modules in module planner

[ZhangYiJiang]

Similar to #1911, but a bit more difficult because this requires design help. I imagine a possible UI would be something like whole day events in gcal in week mode, where the events are shown on top of the day's events. Supporting drag and drop would be somewhat difficult though, and if all four semesters are filled, then getting the UI right would be somewhat difficult.