Remove "SoftMu" from derivations
The SoftMu
that we're using in derivations now isn't anything like the one we used in DL1rmu (which we're still working to port to release 21). I don't know of anyone using this, and a lot of warning messages seem to suggest that it's misconfigured anyway, so we should probably turn it off.
I believe @duperrin should take a look at this.
Edited by Dan Guest