[Gtkradiant] Patch for TODO Textures: add anisotropic filtering

[Shaderman]

Thanks for your feedback namespace but I have to contradict :)

I'll quote some parts from the OpenGL specification I found at 
http://www.opengl.org/registry/specs/EXT/texture_filter_anisotropic.txt
> For to Aniso. filtering to work correct, you must have:
> - GL_LINEAR_MIPMAP_LINEAR and GL_LINEAR filtering mode for min- and magfilter
> - mipmaps for all textures
>
> GL_TEXTURE_MAX_ANISOTROPY is not a filtering mode like
> GL_LINEAR or GL_NEAREST, its just a paramter which affects
> these filteringmodes.
> As far as i can tell from the diff, you treat it as a filtering mode.
>   
"A texture's maximum degree of anisotropy is specified independent from 
the texture's minification and magnification filter (as opposed to being 
supported as an entirely new filtering mode). Implementations are free 
to use the specified minification and magnification filter to select a 
particular anisotropic texture filtering scheme."

"Implementations are also permitted to ignore the minification or 
magnification filter and implement the highest quality of anisotropic 
filtering possible."

...but...

"Applications seeking the highest quality anisotropic filtering 
available are advised to request a LINEAR_MIPMAP_LINEAR minification 
filter, a LINEAR magnification filter, and a large maximum degree of 
anisotropy."

I didn't see any difference when min + mag filters were set, but I'll 
change it and send a new patch to the mailing list when I have more 
information about the usability with Linux.

Shaderman