Format SGB with CTWILL

[ascherer]

Please submit *.tch and *.bux files for any of the following modules, listed here by increasing levels of dependency, in order to create *.pdf files like gb_io-ctwill.pdf:

1. gb_flip, gb_graph, gb_io
2. gb_dijk, gb_rand, gb_save, gb_sort
3. gb_basic, gb_econ, gb_gates, gb_lisa, gb_raman, gb_roget
4. gb_books, gb_games, gb_miles, gb_words
5. gb_plane
6. test_flip, test_graph, test_io, test_sample
7. assign_lisa, book_components, econ_order, football, girth, ladders, miles_span, multiply, queen, roget_components, take_risc, word_components

See commit 0aec605 for details about how to use ctwill format.