fix bsearch tables that must be sorted, add comment to all tables that must be sorted

src/sp65/convert.c

@@ -61,7 +61,8 @@ struct ConverterMapEntry {
     StrBuf*             (*ConvertFunc) (const Bitmap*, const Collection*);
 };
 
-/* Converter table, alphabetically sorted */
+/* Converter table */
+/* CAUTION: table must be alphabetically sorted for bsearch */
 static const ConverterMapEntry ConverterMap[] = {
     {   "geos-bitmap",          GenGeosBitmap   },
     {   "geos-icon",            GenGeosIcon     },