Allow events to expand for moused over or touched events in Weekly Caledar

[rsalsbery]

In working on an issue for a customer I found that by adding overflow: visible; with custom CSS to a Weekly Calendar in the CSS below, you could make the event block expand when mousing over it:

.cal-weekly-grid>.grid-item:hover {
    z-index: 10001!important;
    overflow: visible;
}

This allows users to expand the event block on particularly large Weekly Calendars so that they can see the event. I believe this would be a good value add for our Weekly calendar.