Add a add_longoutput function for custom extensions

[Tontonitch]

Hello,

That would be great to have a dedicated method for the extra lines / long output lines. Named for example "add_longoutput"

Currently, I do that via the add_perfdata method by adding a new line and all the needed lines. For example:

$self->add_perfdata(sprintf "broken=%d;;1;0; failing=%d;1;;0; \nBroken jobs:%s\n\nFailing jobs:%s", $nb_broken, $nb_failures, $long_output_broken, $long_output_failures);

Example of output in Icingaweb2: