hyperlink widget

[Xeverous]

This issue is for tracking any decisions before implementing this widget.

Some notes:

• It will very-likely require platform-specific code (by default, on click it should open the link in default browser) - probably place such code in host directory.
• The default appearance (blue color, underline) will require a rich text label widget first. In fact, a hyperlink widget should probably be nothing more than a rich label with predefined on_click function and its blue, underlined text appearance