Fix typo in gobject.Value. Fixes #239

generated/gtkd/gobject/Value.d

@@ -89,7 +89,7 @@ public class Value
 		this();
 		init(GOBJECT.getType());
 
-		static if ( is(GOBJECT : GObject) )
+		static if ( is(GOBJECT : ObjectG) )
 		{
 			setObject(obj);
 		}

src/APILookupGObject.txt

@@ -800,7 +800,7 @@ code: start
 		this();
 		init(GOBJECT.getType());
 
-		static if ( is(GOBJECT : GObject) )
+		static if ( is(GOBJECT : ObjectG) )
 		{
 			setObject(obj);
 		}