Delete bogus local versions of mount*.[ch] and nfs_prot*.[ch].
Use v3 protocol by default for NFS mounts. If v3 is not supported, v2 is
used automatically. Add a new mount options for NFS, 'nfsv2' to allow the
administrator to force the use of the older protocol.
Document the new mount options and fix a couple of markup problems.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
