relax SVN archive

Renamed Peak_intensity to Grid_base in the safeguarded old code.

Created a copy of the spectrum module to convert in the future to a generic editable grid object.

The Peak_intensity GUI element now replaces the ref and sat peak file and RMSD fields.

This GUI element will still need a lot of work to be useful. In the end this will allow people with
replicated NOE spectra to use the GUI.

Removed 'current' from the data pipe field text.

The Observer object no longer uses __init__() to setup structures as the singleton design kills it.

Fix for the new_analysis() method - it should be calling switch_page().

The Pipe_switch_observer singleton has also switched to the object base of Observer.

The Observer class is now using the new style python object construction.

Created the page_switch() method and registered it for pipe switches.

The new page_switch() method is registered with the Pipe_switch_observer singleton and observer
object so that pipe switches cause the notebook to switch pages. The switch_page() method has also
been created to abstract the switching of pages in the notebook.

Created generic_fns.pipes.Pipe_switch_observer for observing switches in the current data pipe.

Pipe_switch_observer.notify_observers() is now called by the switch() and delete() functions.