message: console output restored in slim branch
diff: using boost::container::flat_set;
  namespace eosio { namespace chain {
  +
  +static inline void print_debug(account_name receiver, const action_trace& ar) {
  + if(fc::logger::get(DEFAULT_LOGGER).is_enabled(fc::log_level::debug)) {
  + if (!ar.console.empty()) {
  + auto prefix = fc::format_string(
  + "\n[(${a},${n})->${r}]",
  + fc::mutable_variant_object()
  + ("a", ar.act.account)
  + ("n", ar.act.name)
  + ("r", receiver));
  + dlog(prefix + ": CONSOLE OUTPUT BEGIN =====================\n"
  + + ar.console
  + + prefix + ": CONSOLE OUTPUT END =====================" );
  + }
  + }
  +}
  +
  action_trace apply_context::exec_one()
  {
  const auto& gpo = control.get_global_properties();
  @@ -53,6 +70,8 @@ action_trace apply_context::exec_one()
  t.total_inline_cpu_usage = cpu_usage;
  t.console = _pending_console_output.str();
  + print_debug(receiver, t);
  +
  executed.emplace_back( move(r) );
  total_cpu_usage += cpu_usage;
  