Changes to Template Haskell Library

A proposed change will add the following constructors to TH's Type datatype...

| PromotedListT [Type]    -- for types of the form '[Int, Bool]
| PromotedTupleT [Type]   -- for types of the form '(Int, 'False)

... and the following constructors to TH's Kind datatype:

| ConK Name               -- for kinds of the form Bool
| VarK Name               -- k
| ForallK [Name] Kind     -- forall k. ...

The final Kind constructor does not need any special binder construct because all kinds are of sort BOX.