Refactor named wildcards (again)

Michal's work on #10982, #11098, refactored the handling of named
wildcards by making them more like ordinary type variables.

This patch takes the same idea to its logical conclusion, resulting
in a much tidier, tighter implementation.

Read Note [The wildcard story for types] in HsTypes.

Changes:

 * Named wildcards are ordinary type variables, throughout

 * HsType no longer has a data constructor for named wildcards
   (was NamedWildCard in HsWildCardInfo).  Named wildcards are
   simply HsTyVars

 * Similarly named wildcards disappear from Template Haskell

 * I refactored RnTypes to avoid polluting LocalRdrEnv with something
   as narrow as named wildcards.  Instead the named wildcard set is
   carried in RnTyKiEnv.

There is a submodule update for Haddock.

1 files changed, 0 insertions, 0 deletions

diff --git a/utils/haddock b/utils/haddock
-Subproject a8d1ea9a6735209746b184001e40da26a83f050
+Subproject fef5e32ca541eb70b22d8e8da611e4a2b797e00