Mobile/iPhone/iPad: Allow to close the Details panel

[tordans]

This issue might be part of https://github.com/mapbox/osmcha-frontend – IDK.

Goal: Add areas or buttons that allow to close the details panel.

This WAY-Panel cannot be closed:

Suggestions:

• add a tab-event, outside of the panel, that will close the window when I single-tab the map
• add a close (x)-icon on the top right of the panel that allows to close the panel