Expanded folder operations (Move/Copy)

[DerfJagged]

This PR adds recursive Copy and Move operations for folders and adds "merge" functionality if a file/folder is renamed to an existing name.

Handles these edge cases:

• Folder already exists upon folder copy/move/rename.
  • Asks user if overwrite is OK. Applies to all subfolders and files for this operation.
  • Recursively copies files and folders into existing structure.
  • Shows progress bar for every file.
• File already exists upon file rename.
  • Asks user if overwrite is OK.
  • Deletes destination file and renames source file.
• Folder copy/move to same location attempted.
  • Notify user that folder can't be copied over self and stop.
• Folder copy/move to inside itself attempted.
  • Notify user that folder can't be copied inside itself and stop.