added a test

eo/test/t-eoOptional.cpp

@@ -0,0 +1,27 @@
+//-----------------------------------------------------------------------------
+// t-eoOptional.cpp
+//-----------------------------------------------------------------------------
+
+#include "eoOptional.h"
+
+//-----------------------------------------------------------------------------
+
+typedef T int;
+
+struct MyClass {
+    MyClass(eoOptional<T> my_T = NULL)
+    : actual_T(my_T.getOr(default_T))
+    { }
+private:
+    T default_T;
+    T& actual_T;
+};
+
+int main(int ac, char** av)
+{
+    // Three ways of using MyClass:
+    MyClass mc1;
+    MyClass mc2(NULL);
+    T t;
+    MyClass mc3(t);
+}