relax SVN archive

Implemented the back end of the spectrum.delete user function.

Created the RelaxSpectraError and RelaxNoSpectraError error classes for spectral data.

Implemented the front end of the spectrum.delete user function.

This will be used to delete spectral data from the relax data store. It will be useful in the GUI
if a mistake has been made.

Improvements to the wizard _display_page() method.

The user function class is no longer stored in self.gui.

This is no longer needed, as all the GUI code has been converted.

Fix for the Help->Licence menu entry for the new GUI user function design.

This additionally opens the relax controller window so the user will see the text.

Fixes for the pipe editor window to handle the new GUI user function design.

Fixes for the relaxation data reading GUI element for the new GUI user function design.

Fixes for some of the GUI user function calls from the tree part of the spin viewer window.

Fixes for the GUI user function launching in the model-free auto-analysis tab.