Reorg copy entry-points.  Still 227.
Test a Carmichael number.
Merge branch 'master' of git://i.geek.nz/home/ralph/fpga/disc
Oh look, 2 bytes sitting their waiting to be deleted.  225.
Save a byte by moving the output increment to the start.  224.
Re-organise the squaring loop; saves 5.  219.
If we're composite, let the loop finish.  Trivial impact on perf,
saves 4 bytes.  (215).
Dirty hack, saves 2 bytes 213.
Previous simplifications allow loop simplification, saves 2 (211).
Output expected on test_single.