Blender Git Loki

Commit D31 : Check if the user count needs to be decreased after adding a new BI image texture.

Fixes this problem:

*Go to the Blender (BI) textures tab and open an existing image.
*Hit on the plus sign next to datablock to create a new image.
*Complete the creation process and switch back to the first (loaded) image.
-> The image user count raises... will raise as often as you hit the plus sign