Image perspective correction

This will take a quadrilateral identifying a perspective skewed rectangle in an image, and warp it back to it's original shape.

Determining the aspect ratio of the original item is still not resolved. The technique I attempted to implement for aspect ratio is outlined here: http://research.microsoft.com/en-us/um/people/zhang/papers/tr03-39.pdf and here: http://stackoverflow.com/a/1222855/327471

This addresses issue #16
If you swap in a known aspect ratio (like 1:1 for this example) the perspective correction results are much better. The issue is figuring out the object's original aspect ratio programatically.