- moved fbtex to post.c, made it a ping-pong buffer, added fbos for it.

[demo_prior] / sdr / gamma.v.glsl

void main()
{
        gl_Position = gl_Vertex;
        gl_TexCoord[0] = gl_MultiTexCoord0 * vec4(1.0, -1.0, 1.0, 1.0);
}