new demo to test ATI_fragment_shader, not very creative but easy to know if the outpu...

new demo to test ATI_fragment_shader, not very creative but easy to know if the output is correct. Tests single-pass as well as multi-pass shader (only pseudo-dependant texture read though, and no tex coord swizzling), src and dst modifiers, src repetition, dst masks, constants, and some ops. Both shaders run succesfully with swrast as well as r200.