While working on a bug in the Panel for Ubuntu
(https://bugzilla.ubuntu.com/show_bug.cgi?id=1587), I ran into a problem with
the recent-files code.

When loading icons for the recently used files, gdk_pixbuf_new_from_file() is
being used, which doesn't pass a desired size to the loader backend.

For the SVG backend, this will cause it to load at the file's default size which
might be a lot larger (or smaller) and require scaling.  By using
gdk_pixbuf_new_from_file_at_size() the backend can render the SVG at the correct
size, which saves time and memory since the image doesn't need to be scaled.

Attached is a patch that fixes this.