Build UTF-8 script for MUFI

Depends on #4 (closed)

Now that we have cleaned up assets for official scripts, we need to support non-official ones, like MUFI.

1. download MUFI json export
2. make a python script that loads that json file
3. and build ranges with consecutives characters (like displayed on the chart)
4. to output a new json file in assets/scripts/MUFI.json