Brian Holt's histogram of gradient code: ready for merging

Hi all I'm ready to merge Brian's histogram of gradient code. In order to remove the PIL dependency, I've added a new submodule called "scikits.image.draw", with Bresenheim's algorithm (used to determine the coordinates for plotting a line [or circle--not implemented]). Please have a look and send any comments my way. I'll merge this tomorrow if I don't hear anything back. https://github.com/scikits-image/scikits.image/pull/28 Also, I think the new draw module could be a fun place for people who are new to the project to make a good contribution. For example, I'd like to see a NumPy implementation of Wu's algorithm for drawing lines and circles. Regards Stéfan