Add first C++ module

src/ext.cc

@@ -0,0 +1,13 @@
+#include "ext.hh"
+#include <iostream>
+
+namespace Orca {
+    int counter{ 0 };
+}
+
+void test_cxx(Glyph* gbuf, Mark* mbuf, Usz height, Usz width, Usz tick_number)
+{
+    Orca::counter++;
+    std::cout << "test_cxx()" << Orca::counter << std::endl;
+}
+

src/ext.hh

@@ -0,0 +1,24 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+// clang-format off
+#ifndef ORCA_EXT_HH
+#define ORCA_EXT_HH
+#include "base.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void test_cxx(Glyph * gbuf,
+Mark * mbuf,
+Usz height,
+Usz width,
+Usz tick_number);
+
+
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif //ORCA_EXT_HH