print error message when missing parameter translation.

src/kernel/xmlreader.c

@@ -359,7 +359,6 @@ static int parse_calendar(xmlDocPtr doc)
     xmlXPathObjectPtr xpathCalendars;
     xmlNodeSetPtr nsetCalendars;
 
-    /* reading eressea/buildings/building */
     xpathCalendars = xmlXPathEvalExpression(BAD_CAST "/eressea/calendar", xpath);
     nsetCalendars = xpathCalendars->nodesetval;
     months_per_year = 0;

src/util/language.c

@@ -300,6 +300,9 @@ void init_translations(const struct locale *lang, int ut, const char * (*string_
                 struct critbit_tree ** cb = (struct critbit_tree **)tokens;
                 add_translation(cb, key, i);
             }
+            else {
+                log_error("no translation for %s in locale %s", s, lang->name);
+            }
         }
     }
 }