Use std::array in code_point_set and code_points_multiset classes
#351
| Job | Run time |
|---|---|
| 52s | |
| 3m 12s | |
| 1m 23s | |
| 1m 2s | |
| 1m 3s | |
| 1m 10s | |
| 1m 39s | |
| 21s | |
| 43s | |
| 11m 25s |