Mod.io Support

A recent update has added mod.io support to the game! Now modders can upload mods to mod.io via https://mod.io/g/duel-defense1, and mods can be downloaded and installed in-game in the Mods menu.

mod.io support will work for Linux & Windows. So far, not yet for Web and Android, as it requires a gdextension to work.

An example mod project can be seen at https://github.com/duel-defense/mod-example