A number of BOOST_CHECK_EQUAL calls would result in warnings about signs.
This PR fixes signedness for all expectation values, sometimes resulting in int → unsigned int. No other code changes besides adding/removing U to/from values.
Running make &> make_output_... on master versus on this PR:
0$ wc make_output_*
1 1464 5925 90357 make_output_master
2 613 1469 28370 make_output_signfixed
More than halves the output lines from compiling.