feat(paginatedhashgui): Added addPage() function.

Author: Shuvlyy

src/main/java/fr/hashtek/spigot/hashgui/PaginatedHashGui.java

@@ -180,6 +180,18 @@ public PaginatedHashGui clearPageContent()
 
     /* Page management */
 
+    /**
+     * Adds a new page to the Gui.
+     *
+     * @param   page    Page to add
+     * @return  Returns itself.
+     */
+    public PaginatedHashGui addPage(Page page)
+    {
+        this.pages.add(page);
+        return this;
+    }
+
     /**
      * Creates a fresh new page.
      *
@@ -189,7 +201,7 @@ public Page createNewPage()
     {
         final Page page = new Page(this);
 
-        this.pages.add(page);
+        this.addPage(page);
         return page;
     }