AttentionUnet

Tensorflow implmentations of

1. Unet, https://arxiv.org/abs/1505.04597
2. ResUnet, https://arxiv.org/abs/1512.03385
3. DenseUnet, https://arxiv.org/abs/1608.06993
4. ResUnet + SE, https://arxiv.org/abs/1709.01507
5. ResUnet + Dual Attention, https://arxiv.org/abs/1809.02983
6. RAUnet, https://arxiv.org/abs/1909.10360

Requirements:
Python 3
Tensorflow tested on 1.9.0
numpy