relax SVN archive

Modified the threading execution of the GUI analyses.

The class gui.analyses.execute.Execute has been created to be a base class for all the analysis
threads. The specific analyses then only need to derive from this by providing the run() method.
All of the threaded vs. non-threaded, exception handling, and other threaded properties will then
be handed by this class.

Fix for the sequence data in assemble_data().

Removed an unused import.

Fixed the import of the threading module.

Removed an unused import.

The higher level threading.Thread class is being used rather than thread.start_new_thread().

This matches the NOE analysis changes of r13255.

Docstring fix for the NOE assemble_data() method.

The assemble_data() method no longer returns the 'complete' flag.

This is obvious from the missing data list.

The Rx data is now assembled outside of the thread and a message dialog is shown for missing data.

The missing data was previously printed to stdout (the relax controller or shell), but is now shown
in a dialog.

The execute relax button IDs are now all stored.