[cppad.cpp] expose cppadcg bindings

Author: proyan

src/cppad.cpp

@@ -2,6 +2,10 @@
  * Copyright 2021 INRIA
  */
 
+#ifdef PYCPPAD_BUILD_CPPAD_CODEGEN_BINDINGS
+#include "pycppad/codegen/cppadcg-scalar.hpp"
+#endif
+
 #include "pycppad/cppad.hpp"
 #include "pycppad/cppad-scalar.hpp"
 
@@ -12,6 +16,10 @@ namespace pycppad
   void enablePyCppAD()
   {
     exposeCppADScalar<double>();
-    //exposeCppADScalar<float>();
+
+#ifdef PYCPPAD_BUILD_CPPAD_CODEGEN_BINDINGS
+    codegen::exposeCppADCGScalar<double>();
+#endif
+    
   }
 }