relax SVN archive

Shifted the Scons distribution target functions from 'sconstruct' to 'scons/distrib.py'.

The functions 'self.package' and 'self.gpg_sign' have been shifted into their own file
'scons/distrib.py'.

Initial checkin of code to work with ieee-754 double classes (nan etc)

bug #6503 Uncaught nan in xh_vect from bugman

task #3621 overview: NaN catching function.

Ported r2618 to r2632 from the 1.2 line.

The command used was:
$ svn merge -r2617:2632 svn+ssh://bugman@.../svn/relax/1.2

These changes all relate to the Scons system. The Scons scripts have been completely overhauled.
Bugs have been removed. The help system has been redone. A target for creating the API
documentation using Epydoc has been added.

Fixed a very minor bug in the Scons source packaging target.

The relax version was not being checked because the Depends statement was using 'package_bin' rather
than 'package_src'.

Changed the C module compilation Scons help message.

A completely new Scons help message has been created.

The message (produced after typing 'scons --help') has been formatted to be in the same style as the
relax help message ('relax --help'). A line describing the Scons usage has been added. The result
of providing no target, C module compilation, has been added. Both the 'standard targets' and the
'specific targets' are now described. Every last Scons target is fully described.

Fixed an incorrect comment in the 'compile_user_manual_html()' Scons build target function.

Changed the comments and docstrings of the Scons manual targets.

The PDF or HMTL version is now in brackets after the 'user manual' and 'API documentation manual'
parts.

Modification of the CSS file for the API documentation (HTML version).

The file 'docs/api/epydoc.css' is being modified so that the links are not underlined, change colour
when the mouse is over them, are not in bold, and have the same colouring as the standard
http://nmr-relax.com pages. This makes the API documentation pages fit better with the style of
http://nmr-relax.com.

Added the API documentation creation (using Epydoc) to the Scons scripts.

The Scons target to create the HTML API documentation is called 'api_manual_html'. The
documentation can be created by typing:
$ scons api_manual_html

The function 'compile_api_manual_html()' was added to the 'scons/manuals.py' file. This function
runs the 'epydoc' command. All the Epydoc options are specified in that function.