Wrap the new evaluator type "CHECK".

Make it conditional on the recent libdiffpy version.
TODO: Remove ifdefs in the next micro release.

Author: pavoljuhas

srrealmodule/wrap_PairQuantity.cpp

@@ -347,6 +347,7 @@ python::object eval_asarray(PairQuantity& obj, python::object& a)
 const char* evtp_NONE = "NONE";
 const char* evtp_BASIC = "BASIC";
 const char* evtp_OPTIMIZED = "OPTIMIZED";
+const char* evtp_CHECK = "CHECK";
 
 std::string stringevaluatortype(PQEvaluatorType tp)
 {
@@ -358,6 +359,10 @@ std::string stringevaluatortype(PQEvaluatorType tp)
             return evtp_BASIC;
         case OPTIMIZED:
             return evtp_OPTIMIZED;
+#if DIFFPY_VERSION >= 1003002023
+        case CHECK:
+            return evtp_CHECK;
+#endif
     }
     const char* emsg = "Unknown internal value of PQEvaluatorType.";
     PyErr_SetString(PyExc_NotImplementedError, emsg);
@@ -376,8 +381,15 @@ void setevaluatortype(PairQuantity& pq, const std::string& tp)
 {
     if (tp == evtp_BASIC)  return pq.setEvaluatorType(BASIC);
     if (tp == evtp_OPTIMIZED)  return pq.setEvaluatorType(OPTIMIZED);
+#if DIFFPY_VERSION >= 1003002023
+    if (tp == evtp_CHECK)  return pq.setEvaluatorType(CHECK);
+    python::object emsg = ("evaluatortype must be one of %r." %
+            python::make_tuple(python::make_tuple(
+                    evtp_BASIC, evtp_OPTIMIZED, evtp_CHECK)));
+#else
     python::object emsg = ("evaluatortype must be either %r or %r." %
             python::make_tuple(evtp_BASIC, evtp_OPTIMIZED));
+#endif
     PyErr_SetObject(PyExc_ValueError, emsg.ptr());
     throw_error_already_set();
 }