Add plog function (#4047)
Introduce substitution functors (#4047)
Add flexible rule based substitution system (#4047)
Merge pull request #4057 from dschwen/expb_4047

Add plog() and a nifty new substitution system
Merge commit '7b0a3ce8921dc6c7a9c0e58e2c0948ed99e9332e'