The icon should be created before setting video.
Fix issue with new elements and CEGUI 0.8.
Print texture size when diagnosing.
Fix incorrect generation of blend maps.

This has been an issue for quite some time. The main fault was that the
blend map wasn't correctly generated by interpolating the vertex data
contained in the Mercator Segments; instead the vertex data was used
directly. This lead to off-by-one errors.