Changes

Summary

1. enable multi-builds (again, see also 0c7419d3dd59);
2. explore history more thoroughly;
3. tuned signature;
4. clarified "recent" time: days <= 0 means infinity (no constraint);
5. tuned whitespace;
6. proper exploration of older history: avoid premature fallback on current "rev" (see also d3d5cb2d6866, 6706d6f0afda);
7. clarified signature;
8. tuned output;
9. tuned;
10. tuned message;