* spot/twa/acc.hh: Here.  Also make sure << takes an unsigned
argument.
* spot/twa/twaproduct.cc, spot/twaalgos/compsusp.cc,
spot/twaalgos/product.cc, spot/twaalgos/remfin.cc,
spot/twaalgos/totgba.cc, spot/tests/acc.cc: Adjust.