Combo packs - Curse + custom

[Nincodedo]

The ability to keep a Curse pack up to date and also add your own mods on top of it is something I've seen a few people in the community do. We should be able to add support for that fairly easily.

[Nincodedo]

Mod removal could also be something this could do, but maybe for the version after this is implemented? Not sure how we'd go about that.

[Nincodedo]

Just wanted to note this before I forget. We could have a manifest override that would basically replace any existing project IDs you already have. Anything that is skip download or disabled would get excluded from the pack