Added preview boxes for SO/DLL usage

AlexeyAB

2018-01-24 cc6ab9b3ccf48322b97f7fe096381d5594d198f7

 src/network_kernels.cu

@@ -114,6 +114,7 @@
    state.truth = *net.truth_gpu;
    state.train = 1;
    forward_network_gpu(net, state);
   cudaStreamSynchronize(get_cuda_stream());
    backward_network_gpu(net, state);
}