relax SVN archive

Fixed the Mac detection in the Scons script.

Added the ability of the Scons script to catch Mac OS X.

The linker is then sent the options '-bundle -bundle_loader /usr/bin/python -dynamic' to create the
OS X shared library. Not sure how well this will work.

Removed the '.so' part of the shared library target for compatibility.

Added all the necessary code to the Scons script to build the relaxation curve fitting C module.

Added the shell of an Scons script.

Changed the one line program description.

A number of changes to the code for Art Palmer's Modelfree4 program.

The 'palmer.create()' and 'palmer.execute()' now have the keyword argument 'binary'. If the default
of 'modelfree4' is changed to another name, then the binary file executed will be different. This
is useful for running a different version or a binary which is not in the environment's path.

The precision of the data in the 'mfdata' file has been significantly improved.

The function 'palmer.extract()' has been rewritten to be much more efficient. Rather than walking
through the 'mfout' file line by line for each parameter for each residue, only one parse of the
file is done to work out the position of each section. Then the section position plus the residue
position is added to extract the relevant data.

Updated the release checklist instructions for creating the HTML manual.

Updated the manual and version number to 1.2.1.

relax version 1.2.1.

This release fixes a number of bugs affecting the creation of Dasha scripts for specific model-free
models (two time scale motions but without the tf parameter), and the reading back in of Dasha
results for models with motions on two time scales. The function 'value.write()' which was broken
when trying to write out relaxation data (R1, R2, or the NOE) has been fixed as well.