I went through and cleaned up a large number of the warnings in the AthDerivation build. The only warnings remaining are the ones that require some restructuring, or some closer look to make sure they aren't pointing to actual mistakes. Somebody should probably lean on the domain experts to fix those remaining warnings.
I broke this up into a large number of commits, one per package, to make it easier to sweep between releases if we ever need to; as such please don't squash the commits. Also, in most cases I purposely only commented out old code instead of removing it, to leave it for the domain experts to decide whether that code should go or not.