Replace multiple isexpected.to containfile() for the same file with a single
isexpected.to containfile() with instead multiple .withcontent() or .withoutcontent()
for improved readability and preformance.
The attempt to simplify the template by letting flatten() take care of the different
allowed data-types for servers,peers, and pools, was unfortunately a bit too
optimistic. The result was that join(' ') on a Array with empty element created a extra
space caracter when $chrony::servers was a hash with a key but no value.
This is a patch-serie with some added type constraints. I have also fixed the doc-strings where i found that they didn't match the code. And this time REFERENCE.md is not manyally edited, but regenerated for each change.