autogenerate the map_[##].dat nbt files for minecraft map art.
the values of the variables on the first two lines in mc map nbt.py need to be changed to the minecraft path (which varies by system and is easy to look up), and the world name. this only needs to be done once
set image to the image path, mapswide and mapstall to the dimensions of the display, and map_id to the first map id # to be used.
it resizes the given image so its pixel ratio is 1:1 to the right size grid of maps (128x128 'pixels' each). Then it determines which of the 204 allowable map colors is closest to each pixel and writes these to a gz'd nbt file. If the locked tag is set (it is by default), the map will not change even when close enough to its coords that it normally would.