Changes in preparation and execution scripts

* We now use the single-user mode to launch the queries. This avoids
  the creation of other processes, which simplifies profiling and future
  executions on the simulator greatly.
* Both 'runone' and 'runall' scripts now execute each query 3 times, the
  first just captures the execution time using '/usr/bin/time', the
  second uses perf to collect data for the callgraph, and the third uses
  'perf stat' to gather a few basic statistics. This gathered statistics
  need to be adjusted, for now we gather the default set perf gives us.