relax SVN archive

The proceed_on_error flag is now taken into account by the wizard's finish button.

The Rx peak list wizard now no longer skips to the next page when an error occurs.

The sync flag is now set for all the pages.

All GUI user functions now use the base page execute() method instead of the interpreter directly.

Created the user function base page execute() method for running the user functions.

This will launch the interpreter in either asynchronous or synchronous mode dependent on the sync
flag.

The sync flag is now set for all of the pages of the NOE peak list wizard.

The UF_page base class now accepts the 'sync' argument.

This will be used to allow for asynchronous or synchronous operation.

The NOE peak list wizard should now stop proceeding on all errors.

Modified all of the gui_to_*() functions to catch a real None input value.

Fix for the new gui_to_str_or_list() function.

Bug fix for the structure.read_pdb GUI user function.

The values from the GUI are now converted to the correct form.