GitLab

* Performance improvements
* Support for splitting CPU meters into two or four columns
  (thanks to Wim Heirman)
* Switch from PLPA, which is now deprecated, to HWLOC.
* Bring back support for native Linux sched_setaffinity,
  so we don't have to use HWLOC where we don't need to.
* Support for typing in user names and column fields in selection panels.