Translatable strings for simplewallet

The system is mostly the Qt system, but we don't use Qt to avoid
the dependencies.

See README.i18n for details.

src/simplewallet/simplewallet.h

@@ -57,6 +57,9 @@ namespace cryptonote
    */
   class simple_wallet : public tools::i_wallet2_callback
   {
+  public:
+    static const char *tr(const char *str) { return i18n_translate(str, "cryptonote::simple_wallet"); }
+
   public:
     typedef std::vector<std::string> command_type;
 
@@ -165,7 +168,7 @@ namespace cryptonote
 
         if (std::chrono::milliseconds(1) < current_time - m_print_time || force)
         {
-          std::cout << "Height " << height << " of " << m_blockchain_height << '\r';
+          std::cout << QT_TRANSLATE_NOOP("Height ", "cryptonote::simple_wallet") << height << " / " << m_blockchain_height << '\r';
           m_print_time = current_time;
         }
       }