relax SVN archive

Fix for the pipes argument for the structure.align user function in the GUI.

Whitespace fixes for the lib.arg_check module.

Modified the lib.arg_check.is_int_list() function to accept the list_of_lists Boolean argument.

This updates the function to have the same functionality as is_str_list(), allows for lists of lists
of int to be checked.

Registered the new user function argument type 'int_list_of_lists' in the prompt UI.

This is to allow for lists of lists of integers, as used for the model argument in the new
structure.align user function.

Created the frontend of the structure.align user function.

This is almost the same as that of the structure.superimpose user function except that the pipes
argument has been added and the titles and description changed to indicate the differences.

Created the Structure.test_align system test.

This will be used to test the yet to be implemented structure.align user function. This user
function will be similar to the structure.superimpose user function but will be designed so that
structures with different primary and atomic sequences can be superimposed.

Implemented the backend of the structure.mean user function.

This primarily occurs within the internal structural object in the new mean() method. The
pipe_control.structure.main.mean() function simply checks if the current data pipe is correctly set
up and then calls the structural object mean() method.

Some fixes and additional checks for the Structure.test_mean system test.

Import fix for r26099.

Converted all of the pipe_control.strucuture.main functions to use the check_structure() object.

This standardises and improves all of the checks.