Beta: Overlay Rectangle

On request, I've added a follow-on to the You Are Here feature in Beta for iframe:

Overlay Rectangle:

• Specify ox, oy, ow and oh as the x, y, width and height of an overlay box in map coordinates.
  
• This is rendered as a translucent overlay on top of the map. The appearance is hard-coded.
  
• This is supported for IFRAME only. There is no option for the user to move or remove the overlay.
• The details of this API are subject to change without warning.
  

Atlas of the Imperium coverage area:
http://www.travellermap.com/iframe.htm?ox=-111.95&oy=80&ow=166.614&oh=200

Spinward Marches:
http://www.travellermap.com/iframe.htm?ox=-112.104&oy=80&ow=27.776&oh=40 Ω