Add a dry run feature

[Zejnilovic]

Background

The tool is supposed to be "destructive" if run till the end. So for security and understanding the tool we should implement a dry run feature. This means the tool will be run and go through the files, but instead of changing them, it will only show what it will change to the STDOUT or a file.

Feature

Implement a switch/command-line option to be able to run the tool. It goes through all the files but instead of changing them, it only prints the planned changes.