Map upgrades

Right now, maps only work in the world they were created in, which is kind of stupid. Maps should instead of having a number system per world should have a data value for each map that shares the same content as it does (so it can stack, measures pixel by pixel) This would allow players to share map art in game, a way to prevent changes to occur to a map if you wanted to see what it looked like before, allow players to reuse the same area multiple times for creating map art, and would allow general easier use for people who want fonts/letters for maps in item frames, as otherwise would require each letter of each font to be built in the world and take up space, or for laggy plugins that the server host has to download.