RwgTex: Added 4x scaling. This is done by double applying 2x scale filter. Each pass can have its' own scale filter (by default second scaler = first scaler). This feature adds new commandline parms: -4x and -scaler and also new exe-name switches: -4x -2bilinear, -2bicubic, -2bspline, -2catmullrom, -2lanczos, -2scale2x, -2super2x. Not that first scaler always set the second scaler. So second scaler keys must be after first one (-2x-nearest-2bilinear is correct). New option groups: scaler2 and scale_4x. For 4x scale, the power-of-two rescale is applied on second pass.