relax SVN archive

Merged r2528 to r2551 of the 1.2 line into this 'nan_catch_test' branch. This is to syncronise the
branch with the 1.2 line prior to merging the branch back into the 1.2 line.

The command used was:
svn merge -r2528:2551 svn+ssh://bugman@.../svn/relax/1.2

Commented out the calls to 'isnan()' and 'isinf()' in the model-free code.

Added a skeleton for the isnan() and isinf() functions. Two dummy functions have been created and
the code in 'specific_fns/model_free.py' now points to these.

Reverted the last changes to remove the RelaxWarning system code which Chris MacRaild has recoded
within the 'warning' branch.

The command used to revert the changes was:
svn merge -r2532:2531 svn+ssh://bugman@.../svn/relax/branches/nan_catch_test

Added a try statement to catch the ImportError failure of the 'lstat' and 'symlink' functions of the
'os' module within the 'sconstruct' script.

This is a fix for bug #6841 (https://gna.org/bugs/?func=detailitem&item_id=6841) which was reported
by Daniel Perez in the post at https://mail.gna.org/public/relax-users/2006-09/msg00000.html
(Message-id: <44F7FFCF.4060102@...>). The sconstruct function problems were identified
by Chris MacRaild at https://mail.gna.org/public/relax-users/2006-09/msg00003.html (Message-id:
<1157109851.28764.964.camel@...>).

This import statement fails under MS Windows as the symlink 'os' functions are UNIX only.

Added a try statement to catch the ImportError failure of the 'spawnlp' function of the 'os' module.

This is a fix for bug #6841 (https://gna.org/bugs/?func=detailitem&item_id=6841) which was reported
by Daniel Perez in the post at https://mail.gna.org/public/relax-users/2006-09/msg00000.html
(Message-id: <44F7FFCF.4060102@...>). The 'spawnlp' function problem was identified by
Chris MacRaild at https://mail.gna.org/public/relax-users/2006-09/msg00003.html (Message-id:
<1157109851.28764.964.camel@...>).

This import statement fails under MS Windows as the 'spawnlp' function is UNIX only.

Fixed some indexing statements in the Open Source infrastructure chapter which were resulting in the
indexing statement appearing in the manual.

Added a try statement to catch the ImportError failure of the 'kill' function of the 'os' module.

This is a fix for bug #6841 (https://gna.org/bugs/?func=detailitem&item_id=6841) which was reported
by Daniel Perez in the post at https://mail.gna.org/public/relax-users/2006-09/msg00000.html
(Message-id: <44F7FFCF.4060102@...>).

This import statement fails under MS Windows as the 'kill' function is UNIX only.

Move RelaxWarning initialisation till after parsing of command line
arguments.

See: mail.gna.org/public/relax-devel/2006-08/msg00088.html

Further modifications to the Warnings system.

Discussed in thread starting
https://mail.gna.org/public/relax-devel/2006-08/msg00082.html