Added new features and functionality to app. Also updated README and USER_GUIDE to reflect the changes.
These new added functions will allow for a more controlled and precise application of the name change operation.
- Added ability to choose top-level folders only, sub-folders only, files only or any combination to be renamed
- Added the ability to control the depth of sub-folders you want to be effected by the name changing operation
- Added a cancel button to cancel the current operation
- The app now refreshes when the operation is completed or canceled