The initial purpose of this is to make sure there are no orphaned
files in the Developer Guide, so we can make a complete map of all the
content there.
- when running benchmark tests, we used to use `-run=xxx` to exclude unit tests; however a more conventional way is to use `-run=^$`, `-run=^$$` here is to excape the $ simbol, otherwise it won't work.
- add info to display benchmark output only
Erik L. Arneson