Integrate hash dialog into status area

The hashing dialog serves no purpose except to provide status information about the ongoing hashing progress. As a result, this information would be better suited to be displayed in the status area of the main window instead of as a separate modal dialog. Having this information available in the status area would reduce toolbar clutter and allow for easier access to the information.

Possible implementation suggestions include making a small, separate progress bar left of the current status bar or to make the entire status bar the progress bar while hashing. The verbose information from the dialog like speed, filename and time left can be included in a pop-up menu on mouse hover. The pause button (not currently implemented) can be either on progress bar click or a separate pause button.