dnsbench - memory and startup time measurement

Rationale

The dnsbench toolset provides hooks and test cases already. I think it should be possible to supply the benchmark function for the measure.sh script so it could do different things like: q/s benchmark, startup time and peak memory, ... Or it could do both things at once.

Steps

1. ✅ Move the core functions like (bench_run) and its helpers to a separate module.
2. ✅ Add a module for measuring peak memory.
   • Memory composition (virtual/rss) should be measured.
   • Memory usage watermark is measured before & after server startup
3. ✅ Separate steps for prep (zone compilation) and startup for some modules.
4. ✅ Measure the steps time and put it in the data files.
5. ✅ Update data2www.sh scripts to generate bar graphs for memory and startup time.

Questions

• The dnsbench is supposed to work with one server at a time. Not good for transfer benchmarking, maybe "OK" for DDNS benchmarking.
• The test case should probably specify WHICH test modules should be run on it.
  • Config file specifies which modules should be run in given test run.
• Memory and startup benchmarks shouldn't require the DISTEL setup, one box is okay.

Related issues: #188 (closed)