Remove border noise

[mrAceT]

First, I'dd like to thank you for you extremely lightweight implementation of dhash!

I've submitted my first update via GitHub desktop, I added the function to remove the outer pixel, to remove border noise. This improves file comparisons for me.

I do have a small question, where do the numbers come from in:
$counts = array(0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4);