Remove duplicate ctrl+alt+left/right handling

These key combinations were registered as accelerator keystrokes in the
tab bar popup menu, but also handled by EditorListener, so they would
switch tabs *twice*. Removing the handling from EditorListener helps to
fix this.

References: arduino#4228

Author: matthijskooijman

app/src/processing/app/EditorListener.java

@@ -45,15 +45,6 @@ public void keyPressed(KeyEvent event) {
       editor.selectPrevTab();
     }
 
-    // Navigation..
-    if ((event.getModifiers() & CTRL_ALT) == CTRL_ALT) {
-      if (code == KeyEvent.VK_LEFT) {
-        editor.selectPrevTab();
-      } else if (code == KeyEvent.VK_RIGHT) {
-        editor.selectNextTab();
-      }
-    }
-    
 //    if (event.isAltDown() && code == KeyEvent.VK_T) {
 //      int line = textarea.getCaretLineNumber();
 //      textarea.setActiveLineRange(line, line + 3);