Do not prevent tab-switching when external editor is used

EditorListener, the class responsible for handling key shortcuts for
switching between tabs, only worked if the text area was editable. It
seems this was still a remnant from when EditorListener handled a lot of
other keystrokes too that modified the actual text (like indenting).
Now, this limitation does not make sense, so just remove it.

Author: matthijskooijman

app/src/processing/app/EditorListener.java

@@ -5,8 +5,6 @@
 import java.awt.event.KeyEvent;
 import java.awt.event.KeyListener;
 
-import processing.app.syntax.SketchTextArea;
-
 public class EditorListener implements KeyListener {
 
   private Editor editor;
@@ -34,11 +32,6 @@ public void keyTyped(KeyEvent event) {
 
   @Override
   public void keyPressed(KeyEvent event) {
-
-    SketchTextArea textarea = editor.getTextArea();
-    
-    if (!textarea.isEditable()) return;
-    
     Sketch sketch = editor.getSketch();
 
     int code = event.getKeyCode();