To show a wireframe image on a canvas.
This class first parsees a wrl file to get the vertices and edges of the object and then showes it
using wireframe representation on the specified canvas. You can use mouse to zoom in, zoom out, or
rotate this object.
VrmlCanvas has a variable of type VrmlModel3D which is used to store the 3D model.
In the method run(), VrmlCanvas uses a VrmlModelParser to parse
the specified wrl file and get the 3D model.