ncli_db: database tool

[arnetheduck]

includes a benchmark tool for now

here's a test I've been running with the first 620 blocks from witti:

[arnetheduck@tempus ncli]$ ./ncli_db --databaseDir:../build/data/shared_witti/db/ --cmd=bench

devel:

All time are ms
     Average,       StdDev,          Min,          Max,      Samples,         Test
    1787.845,        0.000,     1787.845,     1787.845,            1, Initialize DB
       0.505,        0.364,        0.308,        8.513,          619, Load block from database
      34.672,        0.000,       34.672,       34.672,            1, Load state from database
     131.484,       71.980,      106.325,     1698.509,          619, Apply block

After #1073 (before @zah copy fixes)

All time are ms
     Average,       StdDev,          Min,          Max,      Samples,         Test
    1795.354,        0.000,     1795.354,     1795.354,            1, Initialize DB
       0.514,        0.380,        0.312,        8.951,          619, Load block from database
      21.858,        0.000,       21.858,       21.858,            1, Load state from database
     126.029,       74.113,      106.231,     1747.426,          619, Apply block

#1082

All time are ms
     Average,       StdDev,          Min,          Max,      Samples,         Test
    1865.264,        0.000,     1865.264,     1865.264,            1, Initialize DB
       0.532,        0.387,        0.322,        9.053,          619, Load block from database
      22.856,        0.000,       22.856,       22.856,            1, Load state from database
     127.804,       77.397,      102.216,     1836.070,          619, Apply block