fuclean: Also delete empty files created by new grade tool

fuclean.sh

@@ -7,7 +7,9 @@ fi
 
 # Delete empty comments.txts so we can more easily delete empty directories.
 # Otherwise they would still contain this one empty file.
-find . -type f -name "comments.txt" -empty -delete;
+for pattern in "comments.txt" "feedbackText.html" "*_submissionText.html"; do
+    find . -type f -name "$pattern" -empty -delete;
+done
 
 # Delete all empty directories in the directory containing grades.csv
 find . -type d -empty -delete