✅ added progress output for Unicode tests

Travis aborts tests if they do not produce output for 10 minutes. This commit shall fix this.

src/json.hpp

@@ -12914,7 +12914,7 @@ scan_number_done:
 
                 default:
                 {
-                    // we expected a value
+                    // the last token was unexpected; we expected a value
                     expect(lexer::token_type::literal_or_value);
                 }
             }

test/src/unit-unicode.cpp

@@ -34,11 +34,18 @@ using nlohmann::json;
 
 #include <fstream>
 
+size_t calls = 0;
+
 void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);
 
 // create and check a JSON string with up to four UTF-8 bytes
 void check_utf8string(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
 {
+    if (++calls % 100000 == 0)
+    {
+        std::cout << calls << " UTF-8 strings checked" << std::endl;
+    }
+
     std::string json_string = "\"";
 
     CAPTURE(byte1);