Comments and small refactor
Improve pprIfaceStrictSig
Special-case Var in mkRename
Avoid CPR w/w for something that already returns an unboxed tuple
Try hard to avoid useless w/w for (# .. #)-returning things
Leave singleton (# . #) in place if they were already there
Disable avoiding singleton (# #), for compatibility with old code
Clarify the default demand on demand environments

by adding Notes and using easier to understand combinators.