Log Message:
Update ns to 2.27 and take maintainership.

Changes:
  - Changed list-based improvement to allow changing of
  channels. Previously only a single (static) list of nodes
  maintained. Now list of nodes maintained for each channel. Maybe
  extended for mobilenodes with multiple netif (talking to multiple
  channels) once the multiple netif support is in place.
  - Added validation test-suite for RNG in ns.
  - Added modified version of setdest from U. of Michigan. Also added an
  argument to setdest API that defines the version of setdest being
  used.
  - Change the name of dumbPolicy to nullPolicy for consistency with
  diffserv documentations (suggested by Alexander Sayenko
  <sayenko@cc.jyu.fi>)
  - Added list-based improvement to ns-2. Code contributed by Valerie
  Naoumuv (naoumov@inf.ethz.ch). The improvement involves maintaining
  a doubly-linked list to organise mobilenodes based on their
  X-coordinates. When sending a packet only those neighbor nodes are
  considered who are within a circle corresponding to the
  carrier-sense threshold energy level, below which a node cannot hear
  the packet. Improvement on original version where all nodes in
  topology is considered. considerable gain in run-time performance-
  goes down by about 4 to 20 times, depending on the size of the
  topology. The larger the topology and greater the no of nodes,
  greater the improvement seen with the list-based implementation. Pl
  see relevant papaer "simulation of large adhoc networks", appeared
  at MSWiM'03, san diego, USA for details.
  - Added script <color-event.pl> that takes event/color pairs and
  colors pkts in nam output files in order to highlight nam events.
  - Modified ns to build with tcl/tk8.4 and new otcl/tclcl (release
  pending).
  - Diffusion documentation added to ns-manual.
  - Diffusion changes made includes (1)Added tcl example scripts for 2
  phase-pull, push, 1 phase-pull and gear (with push and 2pp)
  scenarios.  For gear and other node-position dependent routing in
  diffusion, need to have a callback to update node positions. since
  the routing filter (like gear) is init'ed before node positions are
  assigned gear doesn't get the correct node positions, hence the
  callback is required. callback would also be reqd to support node
  movements in diffusion in future.  For now start gear filters (in
  tcl scripts) after node positions are assigned to nodes. This will
  go away once callbacks are implemented.  (2)Added fix suggested by
  Andreas Koepke <koepke@ee.tu-berlin.de> for overflow problem in
  lib/main/tools.cc
  - Added worm model to support simulations of Internet worm attacks.
  This model supports different abstract levels in simulations.  It
  simulates a detailed sub-network at packet level, and the rest of
  the Internet with an analytical model (SIR). It supports two worm
  scanning behaviors: random and local-preferred.
  - Added event tracing function for simple-mac and 802.11.  It was
  contributed by <a \ 
href="mailto:singal@nunki.usc.edu">Sushmita</a> to
  support wireless animations.
  - Added directory for nam animations under ns/tcl/edu. Each
  subdirecotry contains on animation, including short description,
  simulation script, trace file, and nam trace.  These animations are
  ready to use in classroom. The current three animations are
  contributed by Sushmita <singal@nunki.usc.edu> as the outcome of her
  directed research project.
  - Integrated support for infrastructure mode in 802.11 MAC. The code
  was was written by Mike Moreton
  - Fixed bug (reported by Fred Stann) in diffusion3 that caused
  overflow while reading time ( > 2147 sec).
  - New module Delayer for introducing delay variation and channel
  allocation delay.  This is useful for modeling the effects of
  wireless links.  Validation tests in "./test-all-links".  Code
  contributed by Andrei Gurtov.
  - Ported SCTP into ns-2. It was actually ported into ns-2.26 by
  Armando L. Caro Jr. <acaro@@cis.udel.edu> and his group at PEL, Univ
  of delaware. The implementation includes a test-suite-sctp and doc
  for sctp (see chapter on SCTP in ns-manual).
  - Added APIs for diffusion filters to node-config command. See
  tcl/ex/diffusion3 for examples. Also changed UIDs in common pkt
  hdr. It now reflects pkt_num_ as in diffusion message hdr.
  - Adding ts_resetRTO_ to TCP to control whether or not a
  timestamp-enabled sender unbacks a backed-off RTO after making a
  valid RTT measurement from an acknowledged, retransmitted packet.
  Validation tests are in "./test-all-tcpOptions" in "tcl/test":
  "./test-all-tcpOptions timeouts_sack2" (with ts_resetRTO_ true)
  "./test-all-tcpOptions timeouts_sack3" (with ts_resetRTO_ false).
  The suggestion and initial code for this change are from Andrei
  Gurtov.  Also adding exitFastRetrans_ to TCP, to fix a problem
  with clean exits from Fast Recovery.  Set to false for the old buggy
  behavior, or set to true for the new good behavior.  The default is
  true.  "./test-all-tcpOptions timeouts_reno_noexitFR" shows the old
  behavior, and: "./test-all-tcpOptions timeouts_reno" shows the fixed
  new behavior.  The problem was that data was sent in response to dup
  acks even after Fast Recovery was over.  From a bug report by Andrei
  Gurtov.
  - Improved portability for C++ namespaces
  (required for gcc-3.2 where the standard C++ libraries like iostream
  are in namespace stl only).
  - Added trace support for smac. The "mactype" info stored in
  simulator is used to trace data as well as mac pkts (smac or
  802.11).
  - Ported diffusion3.2.0 into ns. A lot of changes: all applications
  re-categorized under gear, ping and rmst. Filters have a separate
  dir. gradient now replaced with one-and two-phase-pull-filter under
  filter_core.
  - Changed the defaults for Agent/TCP/Newreno's newreno_changes1_ and
  partial_window_deflation_ to "1", to reflect RFC 2582.
  - Adding avoidReordering_ to DelayLink, set to true to avoid
  reordering when changing link bandwidth or delay.  The code was
  contributed by Andrei Gurtov, and the validation test is in
  ./test-all-links in the directory tcl/test.  The default is for
  avoidReordering_ to be false, for no change in past behavior.