Simple horizontal/vertical intra predictor

subset1 results:
           RATE (%) DSNR (dB)
    PSNR -1.24925 0.0714962
 PSNRHVS -1.68005 0.118698
    SSIM -1.61579 0.0741426
FASTSSIM -1.85896 0.0609082

Conflicts:
	src/decode.c
	src/encode.c