Replace crude self-made addon system with Pf4j and provide first entry points

Allow execution of addons before server pack generated, after, before archive creation and allow adding of new tabs in the GUI.

backend/main/java/de/griefed/serverpackcreator/plugins/swinggui/AddTabbedPane.java

@@ -16,26 +16,26 @@ public interface AddTabbedPane extends PluginInformation {
      * @author Griefed
      * @return {@link JTabbedPane}.
      */
-    JTabbedPane getTabbedPane();
+    JComponent getTab();
 
     /**
      * Get the {@link Icon} for this tabbed pane addon to display to the ServerPackCreator GUI.
      * @author Griefed
      * @return {@link Icon}.
      */
-    Icon getTabbedPaneIcon();
+    Icon getTabIcon();
 
     /**
      * Get the title of this tabbed pane addon to display in the ServerPackCreator GUI.
      * @author Griefed
      * @return String. The title of this addons tabbed pane.
      */
-    String getTabbedPaneTitle();
+    String getTabTitle();
 
     /**
      * Get the tooltip for this tabbed pane addon to display in the ServerPackCreator GUI.
      * @author Griefed
      * @return String. The tooltip of this addons tabbed pane.
      */
-    String getTabbedPaneTooltip();
+    String getTabTooltip();
 }