Calendar doesn't switch to another month when clicks on a day outside of the current month

[mcepl]

Just noticed when playing with the calendar component and looking at #55 that the x-calendar element doesn't have this ability at all.

It could be probably possible to add this functionality with additional event handlers, but it would be awesome if it was available per default.

[dotch]

will be tracked in the calendar repo at mozbrick/brick-calendar#6