Script to plot (and check) background field
Plot wind field and objects
Allow plotting of wind field
Added a final merge based on extrema position

Also increased merge distance to 1500 to reflect maximum diameter of
systems of 1500km.
Removed processing of data

Wind threshold values are now just passed in as parameters
Fixed bug occurring with 0 objects in frame one

Could not calculated triangle surface area before.  Can now.
Revised test script

Wind threshold values are 66th (low) and 95th (high) percentiles.