option to build the BGE without python, uses existing python check (cmake and scons)

when python is disabled videotextures are not built.

source/gameengine/Ketsji/KXNetwork/KX_NetworkMessageSensor.cpp

@@ -158,6 +158,8 @@ bool KX_NetworkMessageSensor::IsPositiveTrigger()
 	return m_IsUp;
 }
 
+#ifndef DISABLE_PYTHON
+
 /* --------------------------------------------------------------------- */
 /* Python interface ---------------------------------------------------- */
 /* --------------------------------------------------------------------- */
@@ -216,3 +218,5 @@ PyObject* KX_NetworkMessageSensor::pyattr_get_subjects(void *self_v, const KX_PY
 		return (new CListValue())->NewProxy(true);
 	}
 }
+
+#endif // DISABLE_PYTHON