Switch -VN - use the old style volume naming scheme

By default RAR volumes have names like 'volname.partNNN.rar', where NNN is the volume number. Using -vn switch it is possible to switch to another, extension based naming scheme, where the first volume file in a multi-volume set has the extension .rar, following volumes are numbered from .r00 to .r99. It may have sense, if you are going to unpack an archive under the plain MS DOS, which does not allow more than one dot in a file name.