Configurable 'default' style theme

[dbauszus-glx]

We would like an interface to configure the style.default for a layer.

The legend for the basic theme should show either a line / or area and an icon based on the default style.

With an editable flag it should be possible to edit.

The strokeColor, strokeWidth, strokeOpacity.

The fillColor, fillOpacity.

The icon.

It should be possible to select any of the svg_symbol types and define the parameter required by each of the symbols.

Select any svg_template loaded and defined the substitute parameter.

Provide an svg url or png.

Define the scale for the icon.

Additionally it should be possible to define an icon array.