MMM-CalendarExt2 module support

[tausen]

This one is a bit tricky because it has way too many features. Basic usage would require configuring:

• a list of known calendars, titles and their URLs (e.g. personal google calendar, work calendar, ..)
• a list of views, view titles and which calendars are shown in each view (e.g. view 1: personal calendars, view 2: work calendars)
• rotation interval between views
• some kind of guide on how to find the calendar URLs with common calendar providers

I'm also using some custom styling based on this example because the default styles don't look very slick. Consider forking MMM-CalendarExt2 and changing the default styles instead.

[tausen]

Configuration is described here:

https://github.com/MMM-CalendarExt2/MMM-CalendarExt2/blob/master/docs/Configuration.md

Note especially:

You should have at least ONE Scene to display your events. Each Scene could have at least ONE View. You can assume each scene as a profile or page. Each View decides how to show events. It must have at least ONE calendar or more. You can choose to show which calendar events and how to be displayed and more by configuration.

I've added some custom css here which picks some nice colors for 6 calendars in pairs, e.g. [cal1,cal2] are blue, [cal3,cal4] are magenta and [cal5,cal6] are green. This covers the simple use-case where there are up to three people using the mirror, each with their own work and private calendar. Then one scene for private calendars and one scene for work calendars.

Seems the custom CSS could be made simpler by setting className to calX, see calendar configuration.

So maybe we can start off with:

• Two scenes and the option to disable one of them
• One view for each scene, with configurable names (e.g. for "Private calendars", "Work calendars", will be shown on screen)
• Configurable list of calendars with color picker (just one of those 3 colors for now) and view picker

User of course does not need to know of "scenes" and "views".