This folder has the "convert_legacy_colors.py" script of Frigcal 4.0.
Unless you are using the full source-code package, unzip the .zip file
here to access this script, along with its inputs and dependencies.

This script is meant only for users of legacy Frigcal 3.0 or earlier.
It converts existing calendar files' color settings to the new preset
category-colors scheme used in Frigcal 4.0.

See the documentation at the top of the script's file for more info.
In short, you'll edit map*.py input files to specify old=>new color
mappings and use new_color_mapping.py to look up new 4.0 color names.

Also here on Linux only, file frigcal-linux.desktop may be used for
do-it-yourself Linux app registration.  See its in-file docs.