Included ext definitions in Python module (currently: lay)

src/pymod/lay/layMain.cc

@@ -25,4 +25,10 @@
 //  to force linking of the lay module
 #include "../../lay/lay/layForceLink.h"
 
+//  to force linking of the ext module
+#include "../../ext/ext/extForceLink.h"
+
+//  NOTE: img, ant, edt and rdb don't need to be force-linked
+//  as they are hard-linked by lay
+
 DEFINE_PYMOD(lay, "lay", "KLayout core module 'lay'")