relax SVN archive

Bug fix for the structure.create_diff_tensor_pdb user function for when no element info is available.

These atoms where the element is not in the PDB file or cannot be determined should have been
skipped.

The print outs for catching exceptions in threads is now going to STDERR rather than STDOUT.

sys.__stdout__ and sys.__stderr__ are no longer being written to.

Saving the relax state from the GUI now shows the busy cursor for user feedback.

After MC sims saving the state can take a few seconds with the GUI frozen, so this feedback is
necessary.

Errors are now handled properly in the interpreter thread for GUI user functions.

Fix for the structure.read_pdb user function because of the changes to the molmol module.

The GUI analysis execution threads are now daemonic to allow relax to exit.

Added a comment about the daemonic thread.

Redesigned how user functions are executed in the GUI so they are queued and launched in a thread.

This allows the GUI to be responsive while the user functions execute. This is only at the level of
the GUI and not the relax interpreter. The execution lock is also acquired to lock up the GUI while
the user function executes.

A special daemon thread called self.gui.interpreter has a queue object so that a series of user
functions can be queued up if needed. The program now also exists with wx.Exit() call to prevent
unhandled exceptions occurring in this daemon thread.

The pipe.create user function page is now using PIPE_DESC to present a list of pipe types for the user.

This gives the descriptive name of the data pipe type rather than the keyword argument values.