web: Add hyperlink functionaly to HideRow

[mhthies]

From the discussion #89: The HideRow widget shall be extended to optionally work as a hyperlink. This means, the full area of each HideRow can react to click events to navigate to a different page or an external URL.

To indicate this possibility to the user, a HideRow with active link destination shall use the CSS property cursor: pointer.

The link destination shall be configurable via a new optional parameter link_destination to HideRow's constructor, which can either take a full URL as a string or a WebPage object or a WebPageRef object, which contains a web page name and a reference to a section within that page, that shall be added as an anchor to the link URL. (see #92 and #93)