message: fixed: failed assert when running tests for more than one iteration,
  ultimately due to uninitialized memory elsewhere.
diff: @@ -106,7 +106,7 @@ void test_interaction_energy(unsigned seed, tee& log) {
  vec center(center_x, center_y, center_z);
  grid_dims gd;
  - for (size_t i; i < 3; ++i) {
  + for (size_t i=0; i < 3; ++i) {
  gd[i].n = sz(std::ceil(span[i] / granularity));
  fl real_span = granularity * gd[i].n;
  gd[i].begin = center[i] - real_span / 2;
  @@ -255,8 +255,7 @@ void test_gpucode(unsigned seed, bool many_iters, tee& log) {
  //time
  test_interaction_energy(seed, log);
  test_eval_intra(seed, log);
  - //TODO: WHY IS THIS BROKEN ARGHHHHH
  - if (false) {
  + if (many_iters) {
  for (size_t i=0; i<1; ++i) {
  seed = std::random_device()();
  test_interaction_energy(seed, log);
  