Integration of calendar syncing with timesheet syncing

[rngadam]

The calendar reference is actually an additional column on the Balance sheet of the spreadsheet.

So we want to:

• move the calendar code to integrate with the spreadsheet code
• read the calendar column value and if it exists and is a valid calendar:
  • create programmatically an updated trigger on that calendar to do the sync on change

Then anyone can create any calendar and associate it to the master spreadsheet.