relax SVN archive

Created the RelaxStrListNumError error class.

Created the RelaxNoneStrListNumError error class.

Fix for the spin.number() user function.

The number can be None to reset the values. This is used in a system test.

The is_str_or_inst() function now checks for the DummyFileObject object as well.

This fixes a system test.

Migrated many more user function classes to the new 'check' and 'base_class' modules.

All unit tests now pass, but not all user functions use the new modules (to be done later).

Created the RelaxNumTupleNumError and RelaxNoneNumTupleNumError error classes.

Created the RelaxNoneStrFileError error class.

Cleaned up and simplified all the functions in prompt.check.

Modified is_num_list() to check for empty lists.

Added the length arg to RelaxNoneListNumError.