Update tmux to 1.7

Upstream tmux 1.7 has been released:
http://sourceforge.net/projects/tmux/files/tmux/tmux-1.7/

Both of the patches that were in the brew recipe have been applied
upstream, so are no longer necessary here.

### CHANGES FROM 1.6 to 1.7, 13 October 2012

* tmux configuration files now support line-continuation with a "\" at the
  end of a line.
* New option status-position to move the status line to the top or bottom of
  the screen.
* Enforce history-limit option when clearing the screen.
* Give each window a unique id, like panes but prefixed with @.
* Add pane id to each pane in layout description (while still accepting
  the old form).
* Provide defined ways to set the various default-path possibilities: ~
  for home directory, . for server start directory, - for session start
  directory and empty for the pane's working directory (the default). All
  can also be used as part of a relative path (eg -/foo). Also provide -c
  flags to neww and splitw to override default-path setting.
* Add -l flag to send-keys to send input literally (without translating
  key names).
* Allow a single option to be specified to show-options to show just that
  option.
* New command "move-pane" (like join-pane but allows the same window).
* join-pane and move-pane commands learn "-b" option to place the pane to
  the left or above.
* Support for bracketed-paste mode.
* Allow send-keys command to accept hex values.
* Add locking around "start-server" to avoid race-conditions.
* break-pane learns -P/-F arguments for display formatting.
* set-option learns "-q" to make it quiet, and not print out anything.
* copy mode learns "wrap-search" option.
* Add a simple form of output rate limiting by counting the number of
  certain C0 sequences (linefeeds, backspaces, carriage returns) and if it
  exceeds a threshold (current default 250/millisecond), start to redraw
  the pane every 100 milliseconds instead of making each change as it
  comes. Two configuration options - c0-change-trigger and
  c0-change-interval.
* find-window learns new flags:  "-C", "-N", "-T" to match against either or
  all of a window's content, name, or title.  Defaults to all three options
  if none specified.
* find-window automatically selects the appropriate pane for the found
  matches.
* show-environment can now accept one option to show that environment value.
* Exit mouse mode when end-of-screen reached when scrolling with the mouse
  wheel.
* select-layout learns -u and -U for layout history stacks.
* kill-window, detach-client, kill-session all  learn "-a" option for
  killing all but the current thing specified.
* move-window learns "-r" option to renumber window sequentially in a
  session.
* New session option "renumber-windows" to automatically renumber windows in
  a session when a window is closed.  (see "move-window -r").
* Only enter copy-mode on scroll up.
* choose-* and list-* commands all use "-F" for format specifiers.
* When spawning external commands, the value from the "default-shell" option
  is now used, rather than assuming /bin/sh.
* New choose-tree command to render window/sessions as a tree for selection.
* display-message learns new format options.
* For linked-windows across sessions, all flags for that window are now
  cleared across sessions.
* Lots and lots of bug fixes, fixing memory-leaks, etc.
* Various manpage improvements.