Modify gradient method, add README.md and tutorials in advbox

Replace v2.dataset with dataset in Transformer

Refine OCR CTC model.

Replace cross_entropy with softmax_with_cross_entropy in Transformer

data load for inference

Fix the softmax in Transformer.

Add decoder init & verify output

Expose acoustic scale in decoder

Revert AsyncDataReader to avoid using shared memory.

1. Add download of data into ctc_read.py
2. Use 'clone' instead of 'get_inference_program'
3. Add time to train log

SE-ResNeXt python script update

Refine train.py for MobileNet-SSD.

Make buffer queues be objects of class AsyncReader.

Add model average option for OCR CTC model