Added the Map2PNG utility and updated the README.

Map2PNG is a tool to turn .MAP into .PNG; see the appropriate README.
Con2PNG got the conToBitmap function for convenience when using as a library.
Included game-palette.txt, a sample palette used to decode images used during gameplay.
The README was split into pieces to support the fact that there are a several utilites now.
README.md remains for general info, Con2PNG.md describes the Con2PNG utility, and Map2PNG.md describes the Map2PNG utility.