* tools/tm-bench: Don't count the first block if its empty
* Try melekes suggestion
* Fix getting the start time so the first block is no longer empty
* Fix changelog entry
* Make code smell better
* tools/tmbench: Fix the end time being used for statistics calculation
Previously we were using the time at which all connections closed in statistics, not
the time after {duration} seconds.
* Use waitgroups for starting up