How add user dll

[Smokeynz]

I've been using txt files, but the problem is you have to streamread and relist and index internally, it works but is kinda resource hungry.

I really like the dll and xml combination, "find it and use it when needed".
Also means you could just about centralise repeat type messaging used across multi mission packs.
Also arguably a bit more user friendly in that more ppl are used to xml editing for simple configs.