Japanese walls/door : improved models + Bugfix

Bug reported by @donat-b due to the use of texture_alpha : when shaders are disabled, the textures are cut
(http://i.imgur.com/nL1tfUJ.png & http://tinyurl.com/ocxefst).

I fixed that in disabling the texture_alpha, which is no longer used in those textures anyways.

Also, improved models with relief.

![screenshot_2493583180](https://cloud.githubusercontent.com/assets/7883281/4967430/d6554d78-6810-11e4-9186-ada9a826a325.png)