Remove node info from image gallery

The gallery pages currently show "posted by X on date" text below each image. This causes two related problems:

- the floated image blocks use a pixel height so they all line up in a grid. However, the text can be of any size, depending on the length of the image's title, the length of the username, and the font size the theme uses. There's no way to account for this in CSS: there's no real way to predict how high the text will be. Chances are, you get info text that runs under the image below, or a too big gap between images.
- it's also a bit wordy. this is just a matter of personal taste :)

I am in favour of removing the text entirely from the gallery. Readers will want to click an image to see the full size anyway, and they'll get the info there.
I could see the point of making it an admin option -- however, this would cause an inconsistency, as whether node info is shown for actual nodes is set in theme options.