Do not store the "data" folder in Sketch

Instead, just the File object when requested. It is not used during
normal operation (just when adding files, or using save as), so no point
in already creating the object in the constructor.

Author: matthijskooijman

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

@@ -30,11 +30,6 @@ public class Sketch {
    */
   private File folder;
 
-  /**
-   * data folder location for this sketch (may not exist yet)
-   */
-  private File dataFolder;
-
   /**
    * Name of sketch, which is the name of main file (without .pde or .java
    * extension)
@@ -71,7 +66,6 @@ public int compare(SketchFile x, SketchFile y) {
     name = mainFilename.substring(0, mainFilename.length() - suffixLength);
 
     folder = new File(file.getParent());
-    dataFolder = new File(folder, "data");
     files = listSketchFiles(true);
   }
 
@@ -146,6 +140,7 @@ private List<SketchFile> listSketchFiles(boolean showWarnings) throws IOExceptio
    * about to be used.
    */
   public File prepareDataFolder() {
+    File dataFolder = getDataFolder();
     if (!dataFolder.exists()) {
       dataFolder.mkdirs();
     }
@@ -214,7 +209,7 @@ public File getFolder() {
   }
 
   public File getDataFolder() {
-    return dataFolder;
+    return new File(folder, "data");
   }
 
   /**