Applicative

Hey Joe, here is a little better implementation of <*>, but there is another problem which I'll probably let you deal with, unless you'll want me to work on it.
In function 'pure' image created of size 1x1, which makes it impossible to apply with other size images. Applicative stuff won't work without it, for instance function 'sum' that sums all elements of the list will give an error on summing list of images. Basically some kind of Unit Type image is necessary that if any operation done on it will return the other image it was applied with, like: 
image + UnitImage = image

Also there was still issue with interpolation, it was causing index out of bounds when I was trying to do rotation. Anyways I got tired of trying to debug it and just rewrote in a slightly different way. Attached is the definition from the book. More importantly I changed the order of the arguments to (ref' im c r) to (ref' im r c) to keep it consistent with (ref im r c) if you wan't to keep it the old way, just swapp the order back, but please add something to the doc explaining it, it took me a while before I noticed it. Btw, whole idea of rows and cols instead of regular x y or width X height takes some time getting used to.
![screenshot from 2013-10-27 14 47 26](https://f.cloud.github.com/assets/2333894/1416316/21f27af4-3f49-11e3-92ef-dd1e262d537c.png)

Let me know if you have any questions.

Alexey