Template Haskell module finalizers are run after a module is type checked.

The essence of this change is that a TExp a now wraps a TH.Exp instead of a
TH.ExpQ. This means:

 * A typed bracket [||...||] now has type Q (TExp tau), where tau is the type of
   the expression in the bracket.

 * A typed splice $(...)  must contain a value of type Q (TExp tau), and has
   type tau.

Previously, typed brackets had type TExp tau, and typed splices had to contain a
value of type TExp tau.

Since declaration splices are now untyped, they can be used anywhere a
declaration is valid, including in declaration brackets.

Also check for illegal typed/untyped bracket/splice combinations.

Right now the syntax for typed expression brackets and splices maps to
conventional brackets and splices, i.e., they are not typed.

This structure now matches that of the type checker.

(without this I get an ASSERT failure)

    commit 1353d1ef
    Author: Simon Peyton Jones <simonpj@microsoft.com>
    Date:   Thu Dec 20 20:13:36 2012 +0000

    Fix over-zealous ASSERT in TcUnify

The caching of goals in the constraint solver led to a
equality-constraint loop even in a really simple program!

    commit b737a453
    Author: Simon Peyton Jones <simonpj@microsoft.com>
    Date:   Fri Aug 31 10:05:03 2012 +0100

    More simplifications to the constraint solver

    * inert_solved becomes dictionaries-only, inert_solved_dicts

    * inert_solved_dicts is used only to cache the result of uses
      of a top level instance declaration, just like inert_solved_funeqs

    * That in turn simplifies xCtFlavor and rewriteCtFlavor, because
      they no longer need a "should I cache" parameter.  (Moreover the
      settings for this parameter were very subtle; it's easy to get
      loops if you cache too much.  Caching only top-level instance
      uses is much safer, and eliminates all these subtle cases.)

Fixes signals004(threaded1,threaded2) on OS X 32.

Fixes T3807 on OS X 32.