list_mgr: weaker locking for large select requests.

Minimize locking for large select requests by using 'read committed'
isolation level.
chglogs: always check nlink value from DB when CLF_UNLINK_LAST is not set.

If a file is opened+unlinked CLF_UNLINK_LAST is not set in the UNLINK record,
because the file still has an opened reference.
Checking the value of 'nlink' maked it possible to detect that
the file no longer has a name in the namespace, and is about
to be removed.
rbh command: remove deprecated options (-F and -t).
chglog reader: acknowledge records when the pipeline is empty,
not taking into account the bufferized records (in changelog reader queue).

Else it result in not acknoledging the records even if there is a very low activity,
before there is always a couple of records in the record queue.
pipeline: distinguish the need for parent_id and name, from the need of fullpath
that may be needed for fileclass matching.
doc: man pages autogenerated from command help.
doc: man pages added to git.
listmgr: retry the whole transaction on server disconnection, not only the current request.

Moved retry management from request execution layer to transaction management layer.
This properly handles DB disconnection, DB deadlock or timeout by restarting
the whole transaction.
packaging: add all mans in dist tarball (created by make dist).
incr. version to 2.5.0-beta3
cosmetic: fix minor stats display.
scan: don't drop entries from DB when the returned error is -ESHUTDOWN.

When running a scan with an inactive OST, entries on this OST
where ignored because lstat() failed on them.
As a result, they were removed from the DB at the end of the scan.
Now, we still update these entries in the DB, to avoid loosing
information about them.

However, this does not prevent from inactive MDC.
entryproc: cosmetic changes in stats display.

don't display 2 stats lines if first_op=last_op,
enlarge total column to fit with 999M entries,
display DB error message for mass_remove.
listmgr: improved traces when handling DB disconnection errors.
listmgr: optimized mass_remove operation (4-5x speedup) at the end of a scan.
man: Added missing mans for robinhood-lhsm