Gallery View Thumbnail Refresh

[sbatchelder]

When paginating to a new page in the Localizations Gallery View, it takes a short time for the old images to be updated by the new ones. This is particularly apparent on pages with 200/lots of thumbnails. This can cause users to scroll down the page and inadvertantly interact with a Localization that hasn't correctly loaded its graphic yet.

Proposed solution: when entering a new page, first remove/blank-out all previous graphics, perhaps adding a buffer wheel indicating that new data is coming.