Updates to fancy imshow widget and ColorMixer

Hey Everyone, I've made some improvements to the fancy imshow widget and the ColorMixer. The ColorMixer now supports a brightness function. And the fancy imshow widget now includes labeled sliders, a function selector combo box, a commit button and a revert button. Basically, changes will persist between combo-box selections, only if you commit changes. Otherwise, the image is reverted to the most recent commit state. The revert button does a hard reset to the very original image. Please grab everything from my io branch and give it a run through. I think the next thing I will add is hsv support and a histogram under the image. Let me know what else you want! Thanks! Chris