[TW-1844] task calendar color coding ignores context

_Nate Faber on 2016-08-16T17:05:46Z says:_

Currently the calendar report completely ignores the context, coloring in due dates regardless if the tasks occur in the current contexts or not.

The report displayed under the calendar when
calendar.details=full
does respond to context, which is dissonant to the displayed view.

I assume this is related to TW-304, but it would be really nice if this could be implemented so that the calendar doesn't get bogged down with irrelevant contexts and their due dates.