[WIP] Tests

This is a work in progress [WiP] pull request to initiate writing tests for the visualization package.
Some things to note:
1. what method should be used for comparing two lists. either by matching each element explicitly.? or is there any specific method

2). Some classes may not have a point_list. ex. Sphere, or Cylinder. So it would be optional arg, in class Shape, and maybe ommited in subclasses __init__().