DebugDrawFactory and our own VertexTestDraw.

This class will have guts that are needed to draw
what we need in our project.
Merge branch 'master' into DrawingCodeForObjects
Now we have an opportunity to draw whatever we want
dependinig on the state of the GraphObject.
This is acoomplished by plugging VertexTestDraw object into
model. (thus world)
Also, moved most of the lower level calculation into Edge/Vertex
so the client doesn't have to worry about those details.
Merge pull request #13 from karpark/DrawingCodeForObjects

Drawing code for objects