WxPython can't load bitmaps from ImageLibraries

We get an error of the form:
```
18:26:10: Error: Can't automatically determine the image format for non-seekable input.
```
and eventually the program crashes. This is because `ImageLibrary` uses zipped images.

While there is probably some solution which unpacks into a filesystem cache, the correct solution may just be to not use zipped libraries; or perhaps even better, deprecate the `ImageLibrary` and replace it with something better.