relax SVN archive

Added a section for the source code repository in the download page.

This follows a message by Edward at:
https://mail.gna.org/public/relax-devel/2011-06/msg00078.html
Message-id: <BANLkTimq=4vfngu+u2WBAuTTsS0nMW+B4A@...>

Added a stretchable spacer to the NOE window so the execute relax button is always at the bottom right.

The peak list grid GUI element now expands within the box it is given.

Generating new user function 'read_xyz()'.

This is Han's patch https://gna.org/task/download.php?file_id=13148 attached to the task
http://gna.org/task/?7404.

The user function 'read_xyz()' was generated in the prompt/structure.py by duplication of
'read_pdb()' and modified accordingly.

Better layout for the base class static text, text control and button addition.

The right hand box in the analysis windows now expands vertically with window resizing.

The results tab now uses the base setup_analysis_element() method to add borders.

The NOE and Rx analysis windows now use the base class build_main_box() method.

Their build_main_box() methods have been renamed to build_left_box() and modified to suit.

Modifying the function test 'test_read_xyz_internal1()'.

This is Han's patch https://gna.org/task/download.php?file_id=13147 attached to the task
http://gna.org/task/?7404.

In the 'test_read_xyz_internal1()' option parser='internal' has been removed.

Shifted the model-free window build_main_box() method to the base class.