A bunch of boot changes. Read carefully.

* Add boot_errno to the nodes table so that nodes can report in a
  subcode to indicate what went wrong. At present, we do not report any
  real error codes; that is going to take some time to work out since it
  will reqiure a bunch of changes to the boot scripts.

* Add new table node_bootlogs to store logs provided by the nodes. Not
  a full console log, but a log of the tmcd client side part. We can
  make it a full log if we want though; just means mucking about with
  the boot phase a bit.

* Add new state transition to NORMALv2 and PCVM state machines. "TBFAILED"
  is a new state that is sent (after TBSETUP) if a node fails somewhere in
  the tmcd client side.

* Change TBNodeStateWait() to take a list of states (instead of single
  state) and an optional pass by reference parameter to return the actual
  state that the node landed in. Change all calls to TBNodeStateWait() of
  course.

* Change os_setup (and libreboot in wait mode) to look for both TBFAILED
  and ISUP. If a TBFAILED event is seen, we can terminate the wait early
  and not retry os_setup on physical nodes (although still retry virtual
  nodes). The nice thing about this is that the wait should terminate much
  earlier (rather then waiting for timeout), especially for virtual nodes
  which can take a really long time when there are a couple of hundred.

* Add new routines dobooterrno() and dobootlog() to tmcd. Bump version
  number and increase the buffer size to allow for the larger packets that
  a console log wikk generate (added MAXTMCDPACKET variable, set to 0x4000).

* Add new -f option to tmcc to specify a datafile to send along as the last
  argument to tmcd. This is more pleasing then trying to send a console log
  in on the command line. For example: "tmcc -f /tmp/log BOOTLOG" will send
  a BOOTLOG command along with the contents of /tmp/log.

  Also close the write side of the pipe so that server sees EOF on
  read. See aside comment below.

* Changes to rc.bootsetup:
     1. Use perl tricks to capture all output, duping to the console and to
        a log file in /var/emulab/logs.
     2. On any error, send a status code (boot_errno) and the bootlog to
        tmcd.
     3. Generate a TBFAILED state transition.

* Changes to rc.injail:
     1. Same as rc.bootsetup, but do not send log files; that would pummel
        boss. Leave them on the physical node.

* Change vnodesetup (which calls mkjail) to watch for any error and send a
  TBFAILED state transition. This should catch almost all errors, and
  dramatically reduce waiting when something fails.

* Changes to rc.cdboot are essentially the same as rc.bootsetup, although a
  bootlog is sent all the time (success or failure), and I do not generate
  a boot_errno yet. Also, instead of TBFAILED, generate a PXEFAILED state
  since the CDROM is actually operating within the PXEFBSD opmode. I have
  yet to work this into the rest of the system though; waiting to get a new
  CD built and actually experiment with it.

* Add new menu option and web page to display the node bootlog. We store
  only the lastest bootlog, but maybe someday store more then one. Display
  boot_errno on node page.

Aside: I made a big mistake in the tmcd protocol; I did not envision
passing more then a small amount of data (one fragment) and so I do not
include a record terminator (ie: close of the write side on the client
sends EOF) or a size field at the beginning. No big deal since small
requests are sent in one fragment and the server sees the entire
thing. Well, with a large console log, that will end up as multiple
fragments, and the server will often not get the entire thing on the first
read, and there are no subsequent reads (with no EOF or known size, it
would block forever). Well, fixing this in a backwards compatable manner
(for old images) was way too much pain. Instead, tmcc now closes the write
side, and the server does subsequent reads *only* in the new dobbootlog()
routine. Note that it *is* possible to fix this in a backwards compatable
manner, but I did not want to go down that path just yet.