Give option to zoom only certain images

Right now, the library zoom every IMG tag when hovered on. There should be a way to specify which IMG tags should be or shouldn't be zoomed.

Possible ways:
- Attributes like `simplezoom` & `no-simplezoom`

More suggestions welcome.

Start by locating the library entry point that handles hover behavior for IMG tags. Review how the proposed simplezoom and no-simplezoom attributes could select images, then confirm the behavior for images that should and should not be zoomed. Done means zoom is no longer applied indiscriminately to every IMG tag.

Written by the indexing model from the issue text.