Add const to read only function

components/esm3/esmwriter.hpp

@@ -44,7 +44,7 @@ namespace ESM
         // Counts how many records we have actually written.
         // It is a good idea to compare this with the value you wrote into the header (setRecordCount)
         // It should be the record count you set + 1 (1 additional record for the TES3 header)
-        int getRecordCount() { return mRecordCount; }
+        int getRecordCount() const { return mRecordCount; }
         void setFormatVersion(FormatVersion value);
 
         void clearMaster();