calendar.store.Events: createDayMap()

[tobiu]

Currently the calendar year view is parsing all calendar events for every single day.

While this works fast for the demo app so far, it can easily become a bottle-neck in case there are 100s of events.

Ideally we need an algorithm which parses all events (records) once and creates a map:

eventMap[yyyymmdd] = [record1, record2,...]