Improve error msg in tcPolyExpr; Simon pls merge into release

- Use explicit file modes when installing binaries & scripts (not essential,
  but someone complained about it).

- Use $(INSTALL_SCRIPT) for scripts

Sigh, another go at getting #line directives right.

Allow unboxed tuple components to have polymorphic types.

Sigh, didn't work in the  cpp, !literate case.

oops, debugging code committed by mistake.

Fix filenames in {-# LINE #-} directives when using both unlit and
hscpp (I think).

fix typo in hppa1.1 support.

remove spurious ^M's

add unofficial/undocumented function:

    mkWeakIORef :: IORef a -> IO () -> IO (Weak (IORef a))

for weak pointers to IORefs.  This avoids some of the problems with
inlining disturbing the semantics of mkWeak by making the weak key
point to the primitive MutVar instead of the box.

Allow mkWeak# to take an unlifted type as the key argument.  The
intention is that boxed-but-unlifted types can be used as keys, not
unlifted types in general but there's no way to enforce this at the
moment.

+RTS -s<blah>  ==>  +RTS -S<blah>

for -Rghc-timing.  The former now gives only summary statistics, as
advertised.

If calling a 'foreign export'ed Haskell function resulted in an error,
localise the error by supplying the module name as well as the name
of the function.

Improve the UI a little for modules contain 'foreign export' declarations -
no longer demand that module name == (basename filename)

Something is very screwy here.  This file does not appear to have been
removed, but it doesn't have any tags beyond 2.04.

Back out yesterday's change to Parser.y, and throw out illegal do
expressions in the renamer instead.  It turned out to be hard to get
the optional semicolons right in the grammar at the same time as
checking that the last statement is an expression.

Add a bit more info about hi-boot files

Do a more correct job of explicit for-alls in types

Add rnfail018

Remove some unused things.

Adopt the following syntax for stmts:

	stmts  -> stmt1 ; ... stmtn ; exp [;]

That is, a do-notation thing must finish with an expression.

Add read009, do-notation

Make Type.isUnLiftedType return True for forall'd unlifted types:
e.g.	x :: forall a. Int#

I found bindings like these were getting floated to the top level.
They are pretty bogus types, mind you.  It would be better never to
construct them.

(George Russell tripped over this one.)

* Fix a bug in the unifier that made the typechecker
  loop on a 5-line program from Sigbjorn.  The bug is
  documented near the fix, in

	TcUnify.uUnboundVar

Add rnfail017

Fix type in tcMatch discovered by Keith

Add tc102

Remove dead token IThash added yesterday by mistake.

Fix use of _unused var for ghc-3.XX.

cpp-ify some H98isms with PSEQ and SAPPLY to placate ghc-3.0X

* Fix a bug in the unifier that made the typechecker
  loop on a 5-line program from Sigbjorn.  The bug is
  documented near the fix, in

	TcUnify.uUnboundVar

Add tc101

Fix trivial parse errors.

More 64bit fun: Fixed an ill-placed #ifdef and added a cast to a
numeric literal (for explanation see yesterday's fix).

Layout fix to uses of ASSERT in do expressions; thanks Kevin for
pointing out the problem.

More 64bit fun: Fixed an ill-placed #ifdef and added a cast to a
numeric literal (for explanation see yesterday's fix).

* Fix long-standing bug in TcIfaceSig which meant it occasionally complained
  about a lint error in an unfolding, with a locally-defined name not
  being in scope.   This only happened when hi-boot loops were being
  tied, so an unfolding might mention a locally-defined name.

* Fix trivial bug in WwLib.mkWWfixup, 
  which showed up when booting the compiler.

More small portability changes:
   * For older GHCs use IOBase instead of PrelIOBase
   * Never use commas in SLIT. cpp IS a hack for Haskell...

Patched my previous patch ($ vs $$, && vs if/then/fi). Installing a
Happy binary-dist still only creates a happy and no happy-1.6
executable, but this has very probably nothing to do with my changes.