Update the dry-run and verbose outputs
    
    The dry-run now returns a much more comprehensible output of what is
    being changed.
    This commit also adds some timing information at the end of the script
    for the time the different steps took, this is helping profiling what
    is taking the most time and thus what should be worked on.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>