Fix wrong Unicode encoding on unsaved sketch

Fixes #4231

Author: facchinm

Diff for: app/src/processing/app/SketchController.java

@@ -674,7 +674,7 @@ private File saveSketchInTempFolder() throws IOException {
     FileUtils.copy(sketch.getFolder(), tempFolder);
 
     for (SketchFile file : Stream.of(sketch.getFiles()).filter(SketchFile::isModified).collect(Collectors.toList())) {
-      Files.write(Paths.get(tempFolder.getAbsolutePath(), file.getFileName()), file.getProgram().getBytes());
+      Files.write(Paths.get(tempFolder.getAbsolutePath(), file.getFileName()), file.getProgram().getBytes("UTF-8"));
     }
 
     return Paths.get(tempFolder.getAbsolutePath(), sketch.getPrimaryFile().getFileName()).toFile();