The state machine of tape drive in the drive catalogue of the tapeserverd
daemon is now the following.  Please note that the actual implementation
of the state machine is not yet complete.

              start daemon /
  ------  send VDQM_UNIT_DOWN   ------------------
 | INIT |--------------------->|       DOWN       |<-------------------
  ------                        ------------------                     |
     |                          |                ^                     |
     |                          |                |                     |
     |                          | tpconfig up    | tpconfig down       |
     |                          |                |                     |
     |      start daemon /      v                |                     |
     |    send VDQM_UNIT_UP     ------------------                     |
      ------------------------>|       UP         |                    |
                                ------------------                     |
                                |                ^                     |
                                |                |                     |
                                | vdqm job /     | SIGCHLD [success]   |
                                | fork           |                     |
                                |                |                     |
                                v                |                     |
                                ------------------    SIGCHLD [fail]   |
                               |     RUNNING      |--------------------|
                                ------------------                     |
                                |                ^                     |
                                |                |                     |
                                | tpconfig down  | tpconfig up         |
                                |                |                     |
                                v                |                     |
                                ------------------      SIGCHLD        |
                               |     WAITDOWN     |--------------------
                                ------------------

 When the tapeserverd daemon is started, depending on the initial state
 defined in /etc/castor/TPCONFIG, the daemon sends either a VDQM_UNIT_UP
 or VDQM_UNIT_DOWN status message to the vdqmd daemon.  Once sent the state
 of the tape drive is either DRIVE_STATE_UP or DRIVE_STATE_DOWN
 respectively.

 A tape operator toggles the state of tape drive between DOWN and UP
 using the tpconfig adminstration tool.

 The tape daemon can receive a job from the vdqmd daemon when the state of
 tape drive is DRIVE_STATE_UP.  On reception of the job the daemon forks a
 child process to run a tape mount session.  A tape will be mounted and
 data will be transfered to and/or from that tape during the session. The
 tape drive is in the DRIVE_STATE_RUNNING state whilst the tape session is
 running.

 Once the vdqm job has been carried out, the child process completes
 and the state of the tape drive either returns to DRIVE_STATE_UP if there
 were no problems or to DRIVE_STATE_DOWN if there were.

 If the tape daemon receives a tpconfig down during a tape session, in
 other words whilst the drive in question is in the DRIVE_STATE_RUNNING
 state, then the state of the drive is moved to DRIVE_STATE_WAITDOWN.  The
 tape session continues to run in the DRIVE_STATE_WAITDOWN state, however
 when the tape session is finished the state of the drive is moved to
 DRIVE_STATE_DOWN.

PollReactorImpl objects own their handlers and therefore need to delete
them where appropriate.  A handler knows when it should be removed from
its reactor and deleted from the heap.  The
PollEventHandler::handleEvent() method a handler now returns true if the
handler wants its reactor to remove and delete it.

Fixed the removal of #ifndef GLOBUS_DONT_DOCUMENT_INTERNAL from previous commit in security headers.

The script used to switch to #pragma once got fooled by their unusual structure.

Fixed h/rfcntl.h which missed multiple inclusion guards entirely.

POLLIN is unfortuntaley not the logical or of POLLRDNORM and POLLRDBAND
on SLC 5.  I therefore replaced POLLIN with the logical or.  I also
added POLLPRI into the mix to cover all possible types of read event.

I have added the values of reqHost and server to the log.

I introduced a bug into sstrerror() when I added error checking code
around the call to Cglobals_get().  The hash of the offending commit is:

ff8021a2

Before my so say improvements, the return value of Cglobals_get() was
not checked.  I added a check that assumed an error had occured if the
return value was non-zero.  Unfortuntaley for me, the return values 0
and 1 both mean success.  A return value of -1 signifies a failure.

The switch statement within TapeDaemon::registerTapeDriveWithVdqm()
was missing a break statment.  This caused an exception to be thrown.

This commit adds code to the tapeserverd daemon to register its
drives with the vdqmd daemon.  There is a problem with the code
in that it fails to register two drives in the up state.  This
will be fixed later.

Added a constraint on MigrationJob.FileSize so that it cannot be <= 0. In particular, this makes sure that we do not try to migrate 0 size file

With this commit tapeserverd connects to the vdqm using Cgethostbyname().
It is planned to replace this use of Cgethostbyname() by getAddrInfo().