Uses Cocoa for GUI part of Vim.

gvim is not a different version of vim, it's just an alias for the GUI part of vim. When starting vim with "-g" option, it's gvim.

Instead of using Carbon in existing gvim, we now try to start a project to adapt Cocoa as the GUI framework.

This project is of course Mac OS X only. We haven't consider to port it to GNUstep yet.