Valo date-picker: date cell hover → active

[jouni]

The selection box should only appear on :active, not on :hover, with the exception of touch devices, where we should not show the :active style when scrolling. That’s not really possible (no [scrolling] state available), so just avoid showing the :active state altogether for touch devices.

Basically, it should work like in the Material theme, you can probably copy-paste it from there: https://github.com/vaadin/vaadin-themes/blob/master/material/vaadin-date-picker.html#L75-L108

[jouni]

This issue was moved to vaadin/vaadin-valo-styles#5