Switch over to the new hierarchical libraries
---------------------------------------------

This commit reorganises our libraries to use the new hierarchical
module namespace extension.

The basic story is this:

   - fptools/libraries contains the new hierarchical libraries.
     Everything in here is "clean", i.e. most deprecated stuff has
     been removed.

	- fptools/libraries/base is the new base package
	  (replacing "std") and contains roughly what was previously
	  in std, lang, and concurrent, minus deprecated stuff.
	  Things that are *not allowed* in libraries/base include:
		Addr, ForeignObj, ByteArray, MutableByteArray,
		_casm_, _ccall_, ``'', PrimIO

	  For ByteArrays and MutableByteArrays we use UArray and
	  STUArray/IOUArray respectively now.

	  Modules previously called PrelFoo are now under
	  fptools/libraries/GHC.  eg. PrelBase is now GHC.Base.

	- fptools/libraries/haskell98 provides the Haskell 98 std.
	  libraries (Char, IO, Numeric etc.) as a package.  This
	  package is enabled by default.

	- fptools/libraries/network is a rearranged version of
	  the existing net package (the old package net is still
	  available; see below).

	- Other packages will migrate to fptools/libraries in
	  due course.

     NB. you need to checkout fptools/libraries as well as
     fptools/hslibs now.  The nightly build scripts will need to be
     tweaked.

   - fptools/hslibs still contains (almost) the same stuff as before.
     Where libraries have moved into the new hierarchy, the hslibs
     version contains a "stub" that just re-exports the new version.
     The idea is that code will gradually migrate from fptools/hslibs
     into fptools/libraries as it gets cleaned up, and in a version or
     two we can remove the old packages altogether.

   - I've taken the opportunity to make some changes to the build
     system, ripping out the old hslibs Makefile stuff from
     mk/target.mk; the new package building Makefile code is in
     mk/package.mk (auto-included from mk/target.mk).

     The main improvement is that packages now register themselves at
     make boot time using ghc-pkg, and the monolithic package.conf
     in ghc/driver is gone.

     I've updated the standard packages but haven't tested win32,
     graphics, xlib, object-io, or OpenGL yet.  The Makefiles in
     these packages may need some further tweaks, and they'll need
     pkg.conf.in files added.

   - Unfortunately all this rearrangement meant I had to bump the
     interface-file version and create a bunch of .hi-boot-6 files :-(