Implement unique IDs and card linking

src/util/string.cpp

@@ -137,14 +137,14 @@ void uncanonical_name_form_in_place(String& str) {
   }
 }
 
-String unified_form(String& str) {
+String unified_form(String& str) {
   str = trim(str);
   for (String::iterator it = str.begin(); it != str.end(); ++it) {
     if (*it == ' ') *it = '_';
     else *it = toLower(*it);
   }
   return str;
-}
+}
 
 String name_to_caption(const String& str) {
   String ret;