Fix palette of Link and NPCs tiles

[zladx]

Fix palette of Link and NPCs tiles

[kemenaran]

Based on a discussion with Aria Hiroshi 64, there should be an easy solution to this:

1. Import the PNG spritesheet into GIMP (or Glimse);
2. Index the image to 4 colors;
3. Change the color map colors (but without changing the color map order);
4. Save the PNG.

At compile time, rgbgfx will still use the color map in the order colors are declared, so it will still compile to the right 2bpp values.

(It seems this is how pokecrystal does it.)

[kemenaran]

(It seems ImageMagik can also be used to convert the PNG to indexed, then to change the colors.)

[ariahiro64]

Check my pull request #260