Drawing code for objects

Custom drawing code now live in VertexTestDraw class.
Also, did some refactoring as well.

For example:

Circle:
public void drawSolidCircle(Vec2 center, float radius, Vec2 axis,

Line:
public void drawSegment(Vec2 p1, Vec2 p2, Color3f color) 

FYI, we shouldn't forget to call same method that belongs to super.