Improved significantly on ProgressBar

Improvements 1,2 and 4 as mentioned in the last commit have been
implemented, i.e., ProgressBar now takes into account files within
sub-folders, the Label now reads properly in the "Save As progress" dialog
box, and "Done Saving" message appears in the message area only after the
entire process is completed.

To do:
1. Ensure progress bar reflects large files accurately
2. Add comments, minor clean-up