Light perl plugins

This is a immature sketch by Nicolai.

Since munin-node is written in perl it should be able to do something like

eval { package privatepluginscope; require "plugin"; }

to get a plugin run, saving a exec and perls startup penalty. We may still want to do the fork, especially since this allows changint the UID of the process and insulates munin-node from any plugins that do unhealthy things.

...Unless there is a magic marker such as #%# extremelytrivial or something to denote that the plugin also executes in trivial time (less than say 1/100th second?)

Nicolai notes that given the negible fork/exec overhead on (most) modern systems this feature offers only complexity without any real upside. Scrap it.