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Not done by default yet, but useful when hacking on libraries.

Roman produced programs involving associated types that did not optimise well.
His programs were something like this:

  data family T a
  data instance T Int = MkT Bool Char

  bar :: T Int -> Int
  bar t = t `seq` loop 0
	where
	  loop = ...

You'd think that the `seq` should unbox 't' outside the loop, since
a (T Int) is just a MkT pair.  

The most robust way to make this happen is for the simplifier to understand
a bit about type-family instances.   See 
	Note [Improving seq]
in Simplify.lhs.  We use FamInstEnv.topNormaliseType to do the interesting
work.

To make this happen I did a bit of refactoring to the simplifier
monad.

I'd previously done a very similar transformation in LiberateCase, but it
was happening too late.  So this patch takes it out of LiberateCase as
well as adding it to Simplify.

Consder Trac #1265, which does this in GHCi:

	Prelude> let doit = fail "Code not written yet" :: ExpQ
	Prelude> $(doit)

Even though 'doit' is defined "in the same module", it's OK to use it in a splice
because it'll have been fully compiled to bytecode.  (Contrast the situation if
these two lines appeared in a single, compiled module.)

Hence we want to bind 'doit' at TH's "imported level" (TcRnTypes.impLevel).  
This used to happen because GHCi-bound Ids were in the *global* type
env (and hence at "imported level").  But since SimonM moved
GHCi-bound ids to the *local* type env (for good reasons) the above
program has been rejected.

This patch makes it work again.

FastTypes - delete ugly _signatures, comment on Bool not FastBool where the typechecker will not catch it

I tested FastTypes.lhs with hugs (manually using cpp) as well as ghc.

Closure uses now a list of Words instead of a ByteArray# to store the non ptrs.
Term.Prim follows this and keeps the [Word] value instead of storing the 
Show representation, which wasn't the best idea anyway.

This fixes test print022

This also means we don't need to carry around 10s of megs of Setup
executables in bindists.

Seemed like a reasonable thing to do, and only 1 line

Reset the exception flag before re-throwing the exception unless it
was "Interrupted".  This avoids needing the double :continue for
ordinary exceptions, but still lets us break on ^C.

when setting a breakpoint by coordinate, if there are no spans
covering the specified coordinate, then we take the leftmost of the
spans to the right of the coordinate.  This means that ':break c' will
work if c is not a function, because the first span will be on c's
right hand side.