relax SVN archive

Ported r2616 from the 1.2 line.

The command used was:
$ svn merge -r2615:2616 svn+ssh://bugman@.../svn/relax/1.2

This removes the ancient unused file 'maths_fns/test.c_chi.py'.

Deletion of the file 'maths_fns/test.c_chi.py'.

This file is an ancient file last touched in 2004. It serves no purpose so has been removed.

The user function 'pdb.read()' still was accepting the arguements heteronuc='N' and proton='H'.

The code of the user function was not using these or passing them on. They have now been removed.

Ported r2612 from the 1.2 line.

The command used was:
$ svn merge -r2611:2612 svn+ssh://bugman@.../svn/relax/1.2

This completes the fixing of bug #7241 (https://gna.org/bugs/?7241).

Ported r2611 from the 1.2 line.

The command used was:
$ svn merge -r2610:2611 svn+ssh://bugman@.../svn/relax/1.2

This adds the directory for Scons Python modules for the Builder functions.

Fixing the rest of bug #7241 (https://gna.org/bugs/?7241).

Bug #7241 was thought to be fixed in in r2591 and r2593, the commit messages describing the solution
being located at https://mail.gna.org/public/relax-commits/2006-09/msg00064.html (Message-id:
<E1GTgBi-0000R6-4h@...>) for r2591 and
https://mail.gna.org/public/relax-commits/2006-10/msg00001.html (Message-id:
<E1GTt6C-0005rk-8q@...>) for r2593.

However this was not the only place that the Scientific Python PDB data structure peptide_chains was
being accessed. The chains were being accessed in the file 'generic_fns/sequence.py' when the
sequence was being read out of the PDB file. This has now been modified with changes similar to
r2591 and r2593.

Created the directory 'scons' for splitting up the 'sconstruct' script into multiple Python modules.

Fix for bug #7336 (https://gna.org/bugs/index.php?7336).

The user function 'pdb.vectors()' was not set up properly. It was expecting the residue number to
be an integer and the residue name to be a string. However the default is that both are set to
None. This was causing a RelaxError.

Fix for bug #7335 (https://gna.org/bugs/index.php?7335).

The code which tests that the proton and heteronucleus have not been set to the same atom name has
been moved from the 'self.read()' function to the 'self.vectors()' function. Two more lines of
code, which were placing the atom names into the 'self.relax.data.pdb' data structure were also
identified to cause similar problems and were shifted from the read to the vectors function.

Fix for bug #7334 (https://gna.org/bugs/index.php?7334).

The problem was that the relax base class in the PDB class of 'prompt/pdb.py' was set to
'self.__relax__'. However two lines were attempting to use 'self.relax'.