Relationship resolver

It would be nice from a UI to have access to all the mods which are in conflict and not pull out a single pair from a exception string.
While there I rewrote some parts. 
It'd be good to know what type `conflicted_mod` is, if we can. There are some places where LINQ has been used and we don't have strong types coming back, but those are mostly my fault. I was new to LINQ, unsure of the types being returned (my older version of MonoDevelop didn't help), and if I got something into a known type quick enough I would hope nobody would notice. ;)