Do not find a tab based on filename, when we have a SketchCode

Filename-based matching is a bit more fragile, so just do a lookup based
on the SketchCode object we already have instead.

Author: matthijskooijman

app/src/processing/app/SketchController.java

@@ -787,7 +787,7 @@ public boolean addFile(File sourceFile) {
         ensureExistence();
         sketch.addCode(newCode);
       }
-      editor.selectTab(editor.findTabIndex(filename));
+      editor.selectTab(editor.findTabIndex(newCode));
     }
     return true;
   }