A point has the following properties:
- an X coordinate
- a Y coordinate
- the point previous to it in the path
- the distance to the point previous to it in the path
- an index which is the sum of the number of points in the ready list and the number of points in the possible path list. The index is calculated after adding the previous point to the ready list and prior to adding the point to the not ready list.
Points are compared on the basis of the distance property.