Webkit dependencies

[Phil Longstaff]

Gnucash on win32 currently uses webkit 1.1.5 from April which I pulled down 
from the net.  I've been working lately on trying to use a more recent version 
(the webkitgtk team is trying to stabilize, and are at 1.1.15.2).  
Unfortunately, webkit now depends on libsoup and enchant, and on win32, 
libsoup includes windows .h files which define GUID, so there's a definition 
clash.  I've hacked around that, for now, but I'm not sure what the best 
solution will be.

Phil