windows terminal patches [2/6]

[Benjamin L. <lin...@gm...>]

Hello,

here's the next patch for the windows terminal:

When developing the copy-to-clipboard code I realised that by virtually 
the same code one can save the EMF file to disk instead of copying it to 
the clipboard.
The attached patch implements a "Save As EMF..." feature for the windows
graph terminal, adds a menu entry and adds a Ctrl+S shortcut for the 
graph window.

benjamin