KML line thickness should be clamped to [some very small value > 0] if 0 line thickness defined

[jng]

When a layer is exported to KML and the line/border thickness specified is 0, such lines will not be shown on Google Earth as the actual thickness value is transferred as-is.

This is not how MapGuide's image-based renderers deal with such a setting. These renderers will still draw said lines presumably with a [very small value > 0] for the line/border thickness.

The KML renderer should follow the same behaviour as the image-based renderers, namely a 0 line thickness is specified in the Layer Definition, it should be replaced with a [very small value > 0] when the KML is written.