Removed Plugin as Super-Interface for many classes, as it may be usefull to create abstract classes that implement, for example, Dice or PlayerCharacterManager that should not appear as plugins themselves (only be the superclass of real plugins).
Also renamed the SRCharacterPanel to allow it beeing used as PC or NPC panel. There will be a "Sumary Character Panel" (for people who don't want to see all player's stats but only the most important ones) soon.