Resize only vertically.

My idea how the image resizing should work.

Resize only too wide, not too high images. I think this is the Right Thing to do. Too high images are just more information than fits on the screen. Scroll to see the bottom bits like you would for a long text.

This ignores the CSS zoom on purpose. Like the the pinch zoom should works the way i think it should:
You start with a large image filling the screen, and when you zoom in the image gets bigger.

Also two bits of clean up:
* Put the JS in an extra file
* use `//` for comments. `/*` and `*/` is a disaster waiting to happen.