snapshot-48

IM improvements

My main focus this time around was to improve the situation for
international users of MacVim.  As a result I also ended up refactoring
keyboard input which will benefit pure ASCII users as well in that it is
now possible to bind to more key combinations than before (e.g. binding
to numeric keypad works).  This refactoing also has the benefit that IM
specific shortcuts work properly (e.g.  Ctrl+Shift+k, Ctrl+j, etc. on
Kotoeri).

First out is better support for the 'noimd' option (which is off by
default nowadays, so you'll have to switch it on first) on Mac OS X 10.5
(sorry 10.4 users, this requires an API which was introduced in 10.5).
Basically, you can use separate keyboard layouts in normal and insert
mode.  For example: use US layout, enable 'noimd', switch to insert mode
and choose another layout.  When you switch between normal and insert
mode these layouts will toggle automatically.  See ":h
macvim-international" for more information.

Secondly, "marked text" (text that is being preedited) is now drawn by
Vim instead of being drawn "on top" of existing text.  I hope this will
be of great use to CJK users in particular (please let me know).

Here are all the changes since snapshot 47:
  - ATSUI clips text to display cell to avoid "bleeding"
  - The pwd is set properly when dropping a folder on the Dock
  - Add Vimball (.vba) as a supported filetype
  - Refactored input code (e.g. can now bind to numeric keypad)
  - Improved IM support (separate keyboard layouts in normal/insert
    modes using the 'noimd' option, see ":h macvim-international")
  - Draw marked text inline (listed as +xim in ":ver")
  - Add user default MMUseInlineIm (use to disable above feature)
  - Update Vim source and runtime files