Added tests (single char pretty printing + op overload)

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

projects/SelfTest/ToStringGeneralTests.cpp

@@ -0,0 +1,40 @@
+/*
+ *  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"
+
+
+TEST_CASE( "Character pretty printing" ){
+    // 
+    SECTION("Specifically escaped"){
+        char tab = '\t';
+        char newline = '\n';
+        char carr_return = '\r';
+        char form_feed = '\f';
+        CHECK(tab == '\t');
+        CHECK(newline == '\n');
+        CHECK(carr_return == '\r');
+        CHECK(form_feed == '\f');
+    }
+    SECTION("General chars"){
+        char space = ' ';
+        CHECK(space == ' ');
+        char chars[] = {'a', 'z', 'A', 'Z'};
+        for (int i = 0; i < 4; ++i){
+            char c = chars[i];
+            REQUIRE(c == chars[i]);
+        }
+    }
+    SECTION("Low ASCII"){
+        char null_terminator = '\0';
+        CHECK(null_terminator == '\0');
+        for (int i = 2; i < 6; ++i){
+            char c = static_cast<char>(i);
+            REQUIRE(c == i);
+        }
+    }    
+}