- Make *mandatory* optional (and default to false); this
allows shorter lists of entries
- Allow degenerate entries which are just a name
(which have *mandatory* set to false as well).
SEE #992
- With refactored code, introducing new kinds of actions
is very few lines of code. Allow disabling targets
(services was already possible). Allow masking units,
but as a special case require the complete name.
FIXES#975
- The three steps of modifying services in the target
system do basically the same thing, so factor out
the loops and logging into a systemctl() function.
- Log to warning() instead of just debugging, on failure.
