#183 - Add new trigger point: PLAYLIST_NEXT

PlayWall/src/main/resources/lang/_de.properties

PlayWallCore/src/main/java/de/tobias/playpad/pad/Pad.java

.../java/de/tobias/playpad/pad/content/PlaylistListener.java

...main/java/de/tobias/playpad/pad/content/Playlistable.java

...tobias/playpad/pad/listener/PadStatusControlListener.java

...aypad/pad/listener/trigger/PadTriggerContentListener.java

...ypad/pad/listener/trigger/PadTriggerPlaylistListener.java

...lCore/src/main/java/de/tobias/playpad/tigger/Trigger.java

.../src/main/java/de/tobias/playpad/tigger/TriggerPoint.java

...ypad/plugin/content/pad/ContentPlayerMediaContainer.scala

.../playpad/plugin/content/pad/ContentPlayerPadContent.scala

...scala/de/tobias/playpad/plugin/content/util/package.scala