snapshot-37

'macmeta', window positioning, etc.

I have done some changes to the communication between MacVim and Vim to
get rid of some potentially dangerous situations, but these kind of
changes also have a way of introducing new problems so be on the
lookout.  (Specifically, the DO connection is only in "event tracking
mode" during live-resize and scrolling to avoid situations where DO
messages arrive e.g. when the menu bar is highlighted as the result of a
Cmd-key being pressed.)

Changes since snapshot 36:
  - Fix bug where Vim would crash when resizing a window with
    double-width characters
  - Add option 'macmeta' to use "alt/option" as meta key to allow
    bindings to <M-..> (see ":h 'macmeta')
  - Add basic support for AppleScript (Jason Foreman).  E.g. to zoom a
    window:
      tell application MacVim
          set zoomed of first window to true
      end tell
  - Fix various bugs relating to initial window positioning
  - Keep window visible on ":set lines=..." and "set columns=..."
  - Inserting text from "Special Characters" palette works again
  - Remove the functionality to use a modifier key as Esc (use the
    PCKeyboardHack app instead, see ":h macvim-hints | /esc")
  - More help on keyboard shortcuts (":h macvim-shortcuts") and the mvim
    script (see ":h mvim")
  - Speed up live resize
  - Support mvim script symlinks to [m|g]ex and rmvim (see ":h mvim")
  - Tentative support for receiving input from system services (Try
    this: insert "2+3", select the text, then hit Cmd-*.  Result: "2+3"
    is replaced with "5".  Sometimes it seems you have to choose
    "MacVim->Services->Script Editor->Get Result of AppleScript" instead
    of pressing Cmd-* for this to work.)
  - No more Vim zombie processes
  - Add "Reload"/"Ignore All" buttons to the file changed dialog
  - (Almost) Latest runtime files, and Vim patches