Provide a W3C global calendar

[vivienlacourba]

A global W3C calendar including the various meetings would be convenient to allow to have a summary view of what is happening globally at W3C.

If should be possible to filter the displayed events based on: groups, types of groups, categories, ...

[swickr]

And, when #5 is implemented the global view should exclude non-public groups.

Perhaps it would be a partial solution for the personal calendar to have an option to include all public groups.

[cwilso]

Incidentally, just to bump this: this would be a really, really useful tool when planning meetings across a spectrum of task-force (and the like) participants, to know how to avoid WG and CG meetings.