relax SVN archive

Generalized the code for selecting the parameters for the different exponentials.

Corrected the header.

Modified the specific function 'relax_fit.select_model()' to handle two of the new exponential names.

The 'exp' function now is named 'exp_2param_neg' and the 'inv' function, 'exp_3param_inv_neg'.

Modified the function 'relax_fit.select_model()' to handle the new exponential names.

Changed the call to the exponential decay function to its new name 'exp_2param_neg'.

Added the equations for different exponenyials.

This was proposed by Ed at:
https://mail.gna.org/public/relax-devel/2011-06/msg00154.html
Message-id: <BANLkTinjNpCCCOa=vbs1asf_zSicQbxvDA@...>

Added SVG and PNG files for the consistency testing icon.

This follows a thread started at:
https://mail.gna.org/public/relax-devel/2011-06/msg00137.html
Message-id: <BANLkTi=981VwxU9PwHG6+yt0G+de-dLmMw@...>

As discussed in this thread, a SVG file is attached, along with 2 PNG files,
one of 200 pixels width, and one of 100 pixels width, the height being scaled
to the image dimension (i.e. 200x94, and 100x47).

Fixes for the initialisation of the UF_panel class.

The parent GUI object is now propagated through the value.set() user function and UF_panel.

The Wiz_panel class now expects a parent GUI element to be set.

This is needed to prevent segfaults.