Drop custom rendering behaviour for image frames in favor of less abstract interface.

[odraencoded]

So image frames have a function to render themselves. Which sounded like a great idea, except for a few factors.

• The image viewer uses Cairo.
• Literally all rendering is done in Cairo.
• Everything is rendered as a Cairo pattern either way.
• Even animated GIFs have their frames converted to patterns.

As you can see, this method has helped in literally nothing!

A better defined way of rendering must be implemented to allow image view to perform optimizations on drawing code, however, custom rendering code in views must be allowed, despite the fact I have no idea what is it ever going to be used for.