Let SketchFile.delete() call Sketch.removeFile()

Previously, callers of `SketchFile.delete()` would also call
`Sketch.removeFile()`, but letting SketchFile handle this is more
robust.

This is possible now that SketchFile keeps a reference to Sketch and
makes updating the Sketch file list less fragile.

Eventually this might be further decoupled by letting SketchFile
broadcast a "deleted" event instead.

app/src/processing/app/SketchController.java

@@ -259,9 +259,6 @@ public class SketchController {
           return;
         }
 
-        // remove code from the list
-        sketch.removeFile(current);
-
         // just set current tab to the main tab
         editor.selectTab(0);
 

arduino-core/src/processing/app/SketchFile.java

@@ -142,6 +142,8 @@ public class SketchFile {
       }
     }
 
+    sketch.removeFile(this);
+
     return true;
   }