Tellico may not show icons

Tellico 0.13.6 may not show the proper cover images in the icon view. Instead, it will show just the default program icon, with the three stacked books. I changed some of the layout code to try to fix a crashing bug, but which now seems to be prematurely deciding that the collection has no image fields. I’ll have it fixed for the next release, which may be a 0.13.7, since I have a couple of other small fixes to include, as well.