Add functions for shot and sensor drawing

Two functions were added to draw spheres at a given X,Y point
on the graph.  The functions are virtually identical, excepting the color
the circles are drawn in (red for shots, blue for sensors).
Impl Straw-man Visual Display

An initial implementation of event plotting is included in this commit.
The included code will
1)Scale the found min and max lon's and lat's to the grid.
2)Iterate through all the shots found IN THIS ITERATION, and add them
to the graph.

This means that old points do not fade or go away, nor do points added
on different polling intervals fit the same scale.  This must be resolved.