Enhancement for better user experience

[afcidk]

• Move notes between directories
  If the notes are not visible from main page, it may be difficult to add one note to other directory.
• Duplicate title in group note function
  User may be able to choose whether to add notes to existing directory or rename the current title of directory.
• Data note existence
  hkmdir-data note should be invisible to users. Though it is removed from history, the note will still show up in personal page.