zone support

[wez]

Another API I was using in pcbnew was InsertArea.

Here's a slightly abbreviated dump of one of the areas that I'd created; I've removed some of the points from the polygon:

  (zone (net 2) (net_name GND) (layer F.Cu) (tstamp 58FCDE74) (hatch edge 0.508)
    (connect_pads (clearance 0.508))
    (min_thickness 0.254)
    (fill (arc_segments 16) (thermal_gap 0.508) (thermal_bridge_width 0.508))
    (polygon
      (pts
        (xy 67.944355 25) (xy 67.944355 25) 
      )
    )
  )

[wez]

(this is useful for ground and power planes)

[wez]

I don't know how much value this adds over the bullet in #9

[dvc94ch]

Fixed