Rxnpatch: Support multiple revisions of clusters.

Prepares for fixing [bug 7225].
Rxnpatch: Support creation of multiple clusters on the same day.

If a cluster already exists, a revision number will be appended
to the timestamp (starting with "-02") to make it unique.

Fixes [bug 7225].
Rxnpatch: Added some cluster creation paranoia.

Cluster creation now aborts (instead of making an invalid tar file)
if a contained filename is too long (ie 100 characters or more).
This is unlikely to ever happen, but...
Merge branch 'grubba/patchsystem' into 5.4

* grubba/patchsystem:
  Rxnpatch: Added some cluster creation paranoia.
  Rxnpatch: Support creation of multiple clusters on the same day.
  Rxnpatch: Support multiple revisions of clusters.
Enable execution of FTP requests in handler threads by -DFTP_USE_HANDLER_THREADS.

Conflicts:
	.gitattributes
Debug: Moved gc histograms to a separate debug flag.

The gc histograms are now enabled with -DLOG_GC_HISTOGRAMS
(or -DLOG_GC_VERBOSE).

Fixes [bug 7197].
Merge branch 'grubba/gc-logging' into 5.4

* grubba/gc-logging:
  Debug: Moved gc histograms to a separate debug flag.
Enable execution of FTP requests in handler threads by -DFTP_USE_HANDLER_THREADS.
FTP: Improved command serialization when FTP_USE_HANDLER_THREADS.

Now uses (a slightly modified) Thread.Queue instead of an ADT.Queue.

Make sure that next_cmd()/low_next_cmd() always is executed from the
backend thread.

Both of the above should reduce issues with race conditions.

Fixes some of [bug 2748].
FTP: Generate the ls(1) output synchronously in handler mode.

Fixes some more of [bug 2748] and [bug 2779].
Merge branch 'patches/bug2748' into 5.4

* patches/bug2748:
  FTP: Generate the ls(1) output synchronously in handler mode.
  FTP: Improved command serialization when FTP_USE_HANDLER_THREADS.
Check index files against dir listing before stat.

This can improve performance a whole lot if the underlying filesystem
is slow.
Check banish list before looking up userinfo.

This can improve performance quite a bit if the underlying user DB is slow,
typically with .htaccess lookups. Also added some defaults mentioned in
[Bug 5956].
FTP: Fixed bug in MLSD/MLST handling.

It failed when there was an active content-type module.

Fixes [bug 7229].
Merge branch 'patches/bug7229' into 5.4

* patches/bug7229:
  FTP: Fixed bug in MLSD/MLST handling.