Allow providing reasons to mod relations

[Martmists-GH]

trafficstars

It's fairly common that mods conflict, break, or suggest other mods. For example, you could have e.g. "suggests": "somelib;reason" which, if available, would load extra functionality, or maybe it'd suggest a compatibility mod. Similar things could be done with breaks/conflicts: linking to issues, or maybe saying "these two mods provide the same thing". While I don't know how this would be implemented, it would definitely be nice to have.

[Earthcomputer]

Is #370 what you want?

[Martmists-GH]

how did I miss that, thanks