relax SVN archive

The 'add()' method now throws a RelaxRunError if the data pipe already exists.

Addition of the 'add()' method to the relax data storage object.

This method will add a new pipe data container to the dictionary using the name of the pipe as the
key.

Shifted all the objects of PipeContainer from the instance scope to the class scope.

Removal of unused import statements.

Shifted the physical constants h, hbar, and mu0 from the PipeContainer class to their own module.

Renamed the class RunContainer to PipeContainer and removed the inheritance from 'object'.

Renamed the data pipe object module (for the name change from 'run' to 'pipe').

Improved the object print out of the relax data storage object __repr__ method.

Modified the __reset__ method of the relax data storage object to remove all the dictionary items.

Added a variable to the relax data storage object for storing the name of the current data pipe.