Finally fixed ProgressBar #4

- If the ProgressBar range would overflow, scale down the values to [0, INT_MAX]
- Now also properly changed order in which checkboxes are checked so that the hashes will be computed in the correct order

Fix progress bar bug

- "Prevent" progress bar from breaking if total file size is 0 (less than 1 KB)

Merge branch 'master' of https://github.com/AlEscher/FileHasher

Added verbose option to headless mode