I have figured out a way to use a class for the line which will be made
up of several circles (At least that's the thought at the moment) joined
together which is the class circle_line with a function that takes the
coordinates of the mouse and upon mouse click draws a circle at that
position. 

I still need to figure out:

- How to get it to draw whilst the mouse button is held down

- How the user will be able to pick the pair of circles they want to
connect and then the program starts drawing a line in that colour