Comments only (about trimming the type environment)
Comments only
Exploit the invariant for AxInstCo to simplify coercionKind
When printing types in the interactive UI, take account of free variables

Often the types we print are full-generalised, but in fact *kinds* are
not, so we need to use tidyOpenType.

Fixes Trac #7587
Merge branch 'master' of darcs.haskell.org:/home/darcs/ghc
Use pprTypeForUser when printing kinds in ghci
Merge branch 'master' of darcs.haskell.org:/home/darcs/ghc