Add onerror bits to various cover images

- Added onerror to hide the display of errored images for:
- Holds and hold history
- Items checked out and checkout history
- Place hold

Signed-off-by: William Rockwood <wrockwood@tadl.org>
Add Video Games as an item type

This makes use of a genre facet / search index on "game".

We're abusing the fi:format of mVG- to distinguish between
video games and other m- selections.

Our approach may change in the future. This is a little bit of a
hack.

Signed-off-by: Jeff Godin <jgodin@tadl.org>