HTML Widgets; widget.UI.HtmlNamedColourToRgb function added

A new function, widget.UI.HtmlNamedColourToRgb has been added.

This will take a named HTML Colour such as "red" and convert it to HTML RGB format, i.e., "#FF0000", e.g.:

var rgb = widget.UI.HtmlNamedColourToRgb("LightBlue");

NOTE: If the named colour is unknown, black ("#000000") is returned and, if the supplied named colour already starts with "#", it will be returned unchanged.