Resize images to fit a reflowable column or scrollable page view.

[jccr]

This adds a new approach for resizing images to fit a reflowable column or scrollable page view.

• It now more actively changes the max-width, max-height values for images, before it would just run once when the iframe doc loaded. Now it runs at every pagination change.
• max-height and max-width values are now calculated and are no longer static CSS percentage based values.
• For scrollable docs the max-height value is not modified.
• It now tries to preserve the original aspect ratio of the resized images.

This attempts to fix the following issues:

• Chrome/Opera/Chromium-only bug (not Safari WebKit): cover image "fit" overflows in next column #144
• Large images are clipped when rendered in two-column mode #138
• Windows 8 Chrome Extension 2.16 Images breaking across columns in reflow #153
• Image "fit resizing" algorithm leads to inconsistent results #88
• Images not resizing to fit the screen in scrollview #64

[coler-j]

This is beautiful and it works like a charm for me. I was reviewing the many many issues related to scrollable image resizing, and this is the only fix that worked for me. Makes more sense to pull it into a helper too for re-usability. Great work!