tools: update (quick)bench tests a little
Today I'm seeing relative performance numbers like this (linode 1G VPS, 32-bit GNU/Linux):

+-------------------------------------------++--------------+--------------+--------------+---------------------+
|                                           || hledger-0.18 | hledger-0.19 | hledger-0.20 | ledger-3.0-20130215 |
+===========================================++==============+==============+==============+=====================+
| -f data/100x100x10.journal     balance    ||         0.16 |         0.04 |         0.05 |                0.02 |
| -f data/1000x1000x10.journal   balance    ||         8.26 |         0.34 |         0.47 |                0.07 |
| -f data/10000x1000x10.journal  balance    ||        11.85 |         2.59 |         3.94 |                0.31 |
| -f data/10000x1000x10.journal  balance aa ||         3.73 |         3.49 |         4.72 |                0.23 |
| -f data/100x100x10.journal     register   ||         0.07 |         0.07 |         0.07 |                0.07 |
| -f data/1000x1000x10.journal   register   ||         0.56 |         0.51 |         0.70 |                0.54 |
| -f data/100x100x10.journal     print      ||         0.06 |         0.04 |         0.06 |                0.01 |
| -f data/1000x1000x10.journal   print      ||         0.37 |         0.34 |         0.49 |                0.07 |
| -f data/10000x1000x10.journal  print      ||         3.84 |         3.54 |         4.62 |                0.55 |
+-------------------------------------------++--------------+--------------+--------------+---------------------+