add -c,-s,-V,-i options: -c change the symlink to target to the specified version. -s handle a specific version for command -L|V|e|r. -V displays available version. -i import extra configuration file from a version to another

allow to use a different version of configuration file than the frontend file if any of -c/m/C is providen. Version symlink point now to the directory instead of the file itself which allow to have extra configuration file