Preprocessing

Preprocessing is done (sorta, kinda, good enough).

Input:
- Some sort of image (see driver.m)

Output:
- Cell array of features, where each cell contains data for a pixel grouping. Features include:

> Width, Height, Pixel Count, Midpoint (by pixel density), X, Y

This closes #4 and contains most of the shit needed for #7 .

As discussed before, I need two people to check this pull request. First person can comment approval, second person comments & merges.

Enjoy!!

Also seems to be reversed.  I believe the first dimension will always be `y`/`height` and the second will be `x`/width.  This is consistent with matrix indexing, where row number precedes column number.