RFC: Renaming of typedef GUID into GncGUID

[Christian Stimming]

Dear all,

finally I've encountered the issue with the type name GUID on windows  
as well: On windows, the system headers define and use heavily a type  
named GUID. However, this will inevitably lead to the declaration  
conflict with our type with this name in src/libqof/qof/guid.h. There  
is just no way out of this conflict. We were able to avoid this in the  
Windows/mingw build so far because glib/gtk went a long way to hide MS  
Windows' system headers from us, but with more GUI programming on  
windows the issue now pops up again.

Hence, I would like to rename our typedef GUID into GncGUID. As you  
can see, the new name would fit into our existing type names very  
well, and it also doesn't terribly confuse its meaning. It is just a  
little bit longer than before.

Comments? Objections?

Regards,

Christian