completely overhaul the plugin system
update debian/control
add .gitignore
update Description and Homepage in debian/control
delete outdated debian/raumzeitmpd*
add .service file, fix debian packaging
use Log::Dispatch in Log.pm

Our hand roled logging functions didn't handle multiline errors.
This also paves the way to use Log::Dispatch::Journald someday.
(it isn't currently packaged in Debian)