Added tests for char tools

Test/Char__IsLetter.cpp

@@ -0,0 +1,19 @@
+#include <CharTools.h>
+#include "Catch2.h"
+
+// Tests character letter-ness by checking it against a map
+TEST_CASE(__FILE__"/MapTest", "[Char][IsLetter]")
+{
+    // Setup
+    const std::string in  = "New album 'Cowboy Tears' out February 18! I am excited!";
+    const std::string map = "1110111110011111101111100111011111111000001011011111110"; // 0 -> no letter, 1 -> letter
+
+    // Verify that I didn't frick up compiling the map by hand
+    if (in.length() != map.length())
+        FAIL("map.size() does not match in.size(). (" << in.length() << " : " << map.length() << ")");
+
+    // Exercise & Verify
+    for (std::size_t i = 0; i < in.size(); i++)
+        if (CharTools::IsLetter(in[i]) != (map[i] == '1'))
+            FAIL("'" << in[i] << "' differs from the map. Map says '" << map[i] << "', 1-> is a letter. Check first if the map is wrong, before trying to debug.");
+}