horsegen: generate koka id lists as public

horsegen/race.kk.template

@@ -14,7 +14,7 @@ extern create-id-table(): vector<int>
   c inline "int32_t arr[] = { {{- range $r := $.Races }}{{ $r.ID }},{{ end -}} };\nkk_vector_from_cint32array(arr, (kk_ssize_t){{ $.RaceCount }}, kk_context())"
   js inline "[{{ range $r := $.Races }}{{ $r.ID }},{{ end }}]"
 // Vector of all race IDs in order for easy iterating.
-val all = once(create-id-table)
+pub val all = once(create-id-table)
 
 val name2id = once()
   var m: rbmap<string, int> := empty()