RegionChooser: Fixing horrible JavaFX heisenbug. `fxapp` was deleted by...

RegionChooser: Fixing horrible JavaFX heisenbug. `fxapp` was deleted by Garbage Collection, which happened very fast with a map.

see https://stackoverflow.com/questions/41903154/javafx-webview-callback-from-javascript-failing-after-garbage-collection

src/eu/simstadt/regionchooser/RegionChooserBrowser.java

@@ -181,6 +181,7 @@ public void importNovaFactoryBoundingBoxes() throws IOException {
 
 	final WebView browser = new WebView();
 	final WebEngine webEngine = browser.getEngine();
+	final JavaScriptFXBridge fxapp = new JavaScriptFXBridge();
 
 	public RegionChooserBrowser() {
 		//apply the styles
@@ -192,9 +193,7 @@ public RegionChooserBrowser() {
 				(ObservableValue<? extends State> ov, State oldState, State newState) -> {
 					if (newState == State.SUCCEEDED) {
 						JSObject win = (JSObject) webEngine.executeScript("window");
-						JavaScriptFXBridge fxapp = new JavaScriptFXBridge();
 						win.setMember("fxapp", fxapp);
-						webEngine.executeScript("fxapp.log('CALLED FROM FXAPP')");
 						webEngine.executeScript("console.log = function(message)\n" +
 								"{\n" +
 								"    fxapp.log(message);\n" +