Added tests (single char pretty printing + op overload)

Tests for issue #809 -- Potentional operator overload ambiguity -- and
PR #646 -- Pretty print characters.

projects/SelfTest/CompilationTests.cpp

@@ -0,0 +1,24 @@
+/*
+ *  Created by Martin on 17/02/2017.
+ *
+ *  Distributed under the Boost Software License, Version 1.0. (See accompanying
+ *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ */
+
+#include "catch.hpp"
+
+
+// This is a minimal example for an issue we have found in 1.7.0
+struct foo {
+    int i;
+};
+
+template <typename T>
+bool operator==(const T& val, foo f){
+    return val == f.i;
+}
+
+TEST_CASE("#809") {
+    foo f; f.i = 42;
+    REQUIRE(42 == f);
+}