Feature - 256-color support

- Integrated new Color object into task.
- Debugging needed - the cyan, green, and yellow colors are mixed up!

src/Color.h

@@ -61,6 +61,8 @@ public:
   std::string colorize (const std::string&);
   std::string colorize (const std::string&, const std::string&);
 
+  bool nontrivial ();
+
 private:
   int find (const std::string&);
   std::string fg ();