Fix colour emphasis support for NTSC filter & raw palette + nes decoder shader

- this implementation is based on a more accurate colour emphasis from fceux.

- The raw palette + nes decoder shader was kinda incomplete since the implementation was based on
a per-frame basis which means that the emphasis bits were read once and applied to the whole frame. This
means that some games that uses a per pixel or per scanline emphasis would not appear correct. The more
accurate implementation reads emphasis bits from bits 5-7 of PPU[1] and saves this info in a separate frame.

- The same implementation is also used to fix emphasis for the ntsc filter.

src/ntsc/nes_ntsc_config.h

@@ -19,7 +19,7 @@ if you enable emphasis above. */
 
 /* Each raw pixel input value is passed through this. You might want to mask
 the pixel index if you use the high bits as flags, etc. */
-#define NES_NTSC_ADJ_IN( in ) (in & 0x3F)
+#define NES_NTSC_ADJ_IN( in, deemp ) ( in & 0x3F ) | ( deemp << 6 )
 
 /* For each pixel, this is the basic operation:
 output_color = color_palette [NES_NTSC_ADJ_IN( NES_NTSC_IN_T )] */