Ported the dyad-independent term templates to C++.

Author: krivit

inst/include/cpp/ergm_changestat.h

@@ -2,6 +2,7 @@
 
 #include "FixedArray.h"
 #include "ergm_modelterm_base.h"
+#include "ergm_network.h"
 
 extern "C" {
 #include "../ergm_changestat.h"

inst/include/cpp/ergm_wtchangestat.h

@@ -2,6 +2,7 @@
 
 #include "FixedArray.h"
 #include "ergm_modelterm_base.h"
+#include "ergm_wtnetwork.h"
 
 extern "C" {
 #include "../ergm_wtchangestat.h"