This class helps to make files writable.
 
 - for the files that are already writable, nothing happens
 
 - for the files that are under source control, if the auto-checkout flag is enabled, the file is checked out
 
 - for the files that are under source control, if the auto-checkout flag is not enabled, the user is asked for confirmation before to checked out the files.
 
 - for the files that are read-only but not under source control, the user is aked for confirmation before to make them writable.
 
 
 Most if not all of this class should be in VCSManager.