Is it possible to style the selected day?

[flsilva]

First, thanks for the awesome open source project!

Is there a way to style the selected day?

The options.theme.selected seems to apply only to the current hovered over day. It'd be great if we could style the selected day in the calendar. That's specially useful when we're editing something, e.g., a task with a due date, and we want to change the due date in a latter time, so we open the calendar again to change it. In such a case being able to see in the calendar the current selected day with a custom style would be very useful for users. We'd have to send the selected date to the Datepicker component, but that's a non issue.