Layer Definition editor defects and loose ends

[jng]

The following defects were observed in the Layer Definition editor for Maestro 3.0 b3

• Deleting a vector scale range does not update the underlying XML content
• Adding a new vector scale range (control) does not create a default (line/point/area) rule controls
• When generating a layer preview, the extents should be modified to fit into the visible scale ranges
• When a particular point style is enabled (The Show XXX style checkbox is ticked), only create a new default rule if the current style has no rules in it