relax SVN archive

The user function container args variable is now private and modifiable.

It needs to be modifiable so the __init__ method can initialise it.

Clean up of the pipe module (removal of useless imports and syntax fixes).

The pipe module is now imported in the __init__ module to set up the data structures.

The user function data object is now imported into the interpreter.

Fix for the Uf_container.__mod_attr__ list.

Removed a duplicate argument.

Added the desc_short arg to the add_keyarg() user function container method.

This arg is used in RelaxErrors for when incorrect parameter are supplied.

Converted the entire of the 'pipe' module to populate the user function data structure.

Big improvements to the user function data container.

The changes are:
- More attributes are now accepted.
- Now only allowed attributes can be modified, to prevent programming errors.
- Docstring improvements.
- More keyword argument data can be input.

Shifted a check from the pipe.create front end to the back end.

Tests do not belong in the front end! And this is not compatible with the new user function design.