Add comments on dixon.py

[imavijit]

Please add comments on dixon.py.It will be easier to understand

[AReallyGoodName]

Note that dixons.py here is not actually Dixons method at all. It's a brute force match of congruence of squares. It squares the numbers and compares those to squares in the factor base. If they equal it outputs the result. This isn't Dixons method. It's a brute force search for equivalent squares.