Merge branch 'multi-in-out' into 'master'

Minor fix mace engine api.

See merge request !268

mace/core/mace.cc

@@ -584,7 +584,6 @@ MaceEngine::MaceEngine(const NetDef *net_def,
     if (!net->Run()) {
       LOG(FATAL) << "Net init run failed";
     }
-    ws_->RemoveUnsedTensor();
     net_ = std::move(CreateNet(op_registry_, *net_def, ws_.get(), device_type));
   }