If you want to add/modify graphical datas in my PT clone, you need to
 run the BMPs through a packer (my packer is supplied - bmp2pth.c/bmp2pth.exe).

Every bitmap (the packed ones) has four colors.

Translation scheme (32-bit RGB to 2-bit palette look-up):
 0x00000000 (palette[0]) -> 0
 0x00BBBBBB (palette[1]) -> 1
 0x00888888 (palette[2]) -> 2
 0x00555555 (palette[3]) -> 3
 (other RGB values = invalid, modify palette[] in pt_palette.c for other colors)

Then each pixel is bit-packed like this (8-bit binary value):
 xx000000 = pixel 1
 00xx0000 = pixel 2
 0000xx00 = pixel 3
 000000xx = pixel 4
 (f.ex. 01001011)

The data is then RLE encoded using the compactor found in ptcompacter.s
 in the PT1.3 source code, except that the "Lowest" (compactor code)
 variable should contain 204 (0xCC) instead of 181 (0xB5).

WARNING:
 Due to the nature of the RLE packer, one 8-bit value is used as an ID to tell
 the RLE unpack routine that RLE data follows. This value is 0xCC (11001100b).
 When translated to 32-bit RGB, this is:
  0x00555555, 0x00000000, 0x00555555, 0x00000000
 (palette[3], palette[0], palette[3], palette[0])

 This means that if these four values are repeated anywhere in the BMP files,
 you will mess up the RLE scheme.

EOF