Fixes some bugs regarding sign drawing and button updating

Fixes a bug displaying a portal as usable even if it's been unregistered
Fixes a bug which causes the portal button to be re-generated, even if the portal has been unregistered

src/main/java/net/knarcraft/stargate/portal/Portal.java

@@ -21,6 +21,7 @@ public class Portal {
     private final String name;
     private final String network;
     private final PortalOwner portalOwner;
+    private boolean isRegistered;
 
     private final PortalOptions options;
     private final PortalOpener portalOpener;
@@ -54,6 +55,24 @@ public class Portal {
         this.portalActivator = portalOpener.getPortalActivator();
     }
 
+    /**
+     * Checks if this portal is registered
+     *
+     * @return <p>True if this portal is registered</p>
+     */
+    public boolean isRegistered() {
+        return isRegistered;
+    }
+
+    /**
+     * Sets whether this portal is registered
+     *
+     * @param isRegistered <p>True if this portal is registered</p>
+     */
+    public void setRegistered(boolean isRegistered) {
+        this.isRegistered = isRegistered;
+    }
+
     /**
      * Gets the location data for this portal
      *

src/main/java/net/knarcraft/stargate/portal/PortalRegistry.java

@@ -231,6 +231,7 @@ public class PortalRegistry {
         }
 
         PortalFileHelper.saveAllPortals(portal.getWorld());
+        portal.setRegistered(false);
     }
 
     /**
@@ -293,6 +294,7 @@ public class PortalRegistry {
         }
 
         allPortals.add(portal);
+        portal.setRegistered(true);
     }
 
 }