relax SVN archive

Fix to allow the spin to target to be set to None in the spin.copy() user function.

Fix to allow the pipes to be set to None in the spin.copy() user function.

The spin user function unit tests now test these functions rather than those of generic_fns.spin.

Copied the spin unit tests for the generic_fns directory to the prompt directory.

Copied the __init__.py file.

Added a directory for adding units tests of the modules in the 'prompt/' directory.

Removed an unused import from the spin unit tests.

Marked the spin user function class as completed within the data model redesign document.

Added the spin.rename() and spin.renumber() user functions to the redesign document.

Updated the identification string documentation for the spin user function class.