[kernel] CommandHandler: merge speedup-replace-istringstream-by-c-strings

- This will gave preformance boost basically with 1 worker, but also a
  small boost for others.

  - With 1 worker:
    - istringstream:
    HSET: 181818.19
    HGET: 212765.97
    ATSET:166666.67
    ATGET:192307.69
    PING: 217391.30
    ```

    - c-strings:
    HSET: 277833.34
    HGET: 303424.25
    ATSET:263157.91
    ATGET:303272.72
    PING: 323161.28

  - With 2 workers:
    - istringstream:
    HSET: 217521.73
    HGET: 270270.28
    ATSET:277944.47
    ATGET:270810.81
    PING: 286000.00

    - c-strings:
    HSET: 222399.98
    HGET: 270621.62
    ATSET:286142.84
    ATGET:277777.78
    PING: 303121.22

  *On Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz, 4 cores*
[utils] build_graphs: add info about commit into folder name
[kernel] Rewrite CommandHandler::split() to use memchr() and make it more beauty

Also this give a small preformance boost.