While conftool is already able to edit and modify values that we would use for mediawiki-config, it has currently no real validation of data we insert this way.
What we need thus is:
- The ability to read values, even complex ones, edit them in an editor, and safely submit them. This is partly possible using the file interface by reading, saving the output to a file, modifying said file, and then issuing a second command to upload the modified file. It would be better if we were able to automate this process in a way that's more solid than a bash wrapper around the process
- The ability to validate individual values against some static meta-validation data, and fail with descriptive error messages.
- The ability to validate individual values against some external program (maybe?)