I realized this didn't let you remove existing mappings without adding them to the output, so I added second commit which introduces the following convention: if you map a file type to the none category, it will be removed.

I'm not very good at naming, so feel free to suggest better names (I was hesitant between --add-filetypes and --add-database, or none and default for instance).

Hey, thanks for the PR. Can you help me understand what is the use case for this? Is the configuration file not enough?

Hi, the goal is the same as in #89: I want to do a few changes to the config file, while preserving the defaults. This way:

• My changes would stand out, I could easily see what changes I applied over the defaults
• The defaults could be easily kept up to date. If I copy all the content from the default filetypes file and then edit it, I won't benefit from future updates, as applying the custom changes over again would be too tedious.

Currently, you can see how I customize my config: I start from what vivid generates, then patch it to my convenience. I thought it would've been much cleaner if vivid had such a feature built-in, then saw the existing issue confirming my thoughts.

I also thought about adding an option such as --output-type=lscolors|pwsh if you'd be ok with that, but started with this PR to see if it'd be accepted. 🙂