WinHugs, Vim support

Hi, This patch provides Vim support. It detects if Vim is installed and allows the user to select it easily without memorising command line options. If anyone has a favourite editor that is not TextPad or Vim, let me know and I'll add support. I would add Emacs support, but I have no idea what a popular port of Emacs is, there seem to be quite a few - anyone who uses one is welcome to let me know. Thanks Neil