bos: Remove MR-AFS commands and options

The blockscanner and unblockscanner commands, as well as many options
to "bos salvage", were only of use to MR-AFS. MR-AFS is not used
anywhere anymore, and these commands and options were largely
undocumented, so get rid of them. See
<https://lists.openafs.org/pipermail/openafs-info/2013-January/039215.html>.
Thanks to Hartmut Reuter for providing information about this.

Change-Id: I496eb4a23a0310aafd6c224a08c76a8b7464c758
Reviewed-on: http://gerrit.openafs.org/10425
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
doc: Add 'checkman' tool

Add the 'checkman' script, which compares a command's "-help" output
to the options actually documented in its manpage. This command is
certainly not perfect, and may contain false negatives and false
positives. It is not (currently) intended to be run as an automated
check, but is meant to assist a human manually checking the
correctness of man pages. An error reported by 'checkman' does not
necessarily indicate something that should actually be changed.

Change-Id: Iae1965c441279dd3f93c1a7283ea0a0140d5ebe3
Reviewed-on: http://gerrit.openafs.org/10442
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>