Patch by Psy-Fi + my minor changes

Adds conformation on exit for windows. Needs to be enabled in user perf.

Tried to edit blender.exe.manifest for more modern dialog look, but didn't work out.

release/scripts/startup/bl_ui/space_userpref.py

@@ -244,6 +244,9 @@ class USERPREF_PT_interface(Panel):
 
         col.prop(view, "show_splash")
 
+        if os.name == 'nt':
+            col.prop(view, "quit_dialog")
+
 
 class USERPREF_PT_edit(Panel):
     bl_space_type = 'USER_PREFERENCES'