Vim: make :W work like "sudo :w"
Vim: make :W work like "sudo :w"

Note how in the GUI version of MacVim, we rely on an external askpass
program, seeing as we don't have a tty and sudo will complain if we try
running it.

Signed-off-by: Wincent Colaiuta <c76ac2e9cd86441713c7dfae92c451f3e6d17fdc@wincent.com>

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent