Changes done to the CLN package.

Version 2.1 on 20 November 2000.
- Removed CGAL/CLN/cl_complex.h, as CGAL doesn't deal with complex numbers.
- Removed cl_dfloat.h cl_ffloat.h cl_lfloat.h cl_sfloat.h, which are basically
  the equivalent of the basic floating point types.
- Removed cl_float.h cl_number.h cl_real.h, which are useless abstract base
  classes.
- Added to_interval().

-------------  CGAL 2.2 is released -------------

Version 2.0 on 23 August 2000.
- Fixed CGAL_NTS compare in the example file.

Version 1.9 on 3 August 2000.
- Moved workaround for Solaris/GCC from src/CLN.C to include/CGAL/CLN/common.h.
- Moved workaround for Quotient<cl_I> from src/CLN.C to CGAL/CLN/cl_integer.h.
- Removed src/CLN.C : this way, libCGAL doesn't depend on CLN anymore !

Version 1.8 on 28 June 2000.
- New maintainer file.
- Removed old workaround for operator>>(Quotient<cl_I>).
  CLN version >= 1.0.2 is required now.
- Namespace NTS introduction.

Version 1.7 on 27 October 1999.
- Added IO include files by default.

Version 1.6 on 12 October 1999.
- Added missing "#include <fstream>".
- New file <include/CGAL/CLN/common.h> which factorizes the common code.

Version 1.5 on 10 October 1999.
- Removed "#include <fstream.h>" to please Visual C++.
- Reference the 1.0.2 version of CLN in the biblio.

Version 1.4 on 7 October 1999.
- Doc updates about installation, and IOs.
- The tests don't fail anymore when CLN is not installed.
  (it's easier to spot the "n" in the test suite if it's not a false alarm)

Version 1.3 on 19 August 1999.
- Added src/CLN.C that initializes the printing base to "10".
  It's done by default, but a bug somewhere prevents this on Solaris...
- Added specialization of operator>>(Quotient<cl_I>).
- Test directory, with a simple test_io.C program.

Version 1.2 on 7 July 1999.
- include files moved to the subdirectory include/CGAL/CLN/.
- removed "#include <cl_io.h>" in each of them.
- made a simple example in examples/CLN/example_cln.C.
- patched install_cgal so that CGAL_USE_CLN is set accordingly,
  as well as the correct flags.

Version 1.1 on 26 June 1999.
- Rewrote the doc.
- Submitted the package to internal releases.

Version 1.0 on 26 March 1999.
- initial version.