fix: model does not stop on stop_training == true #1170

add: loading pickled npy file for imdb dataset loader

# Conflicts:
#	src/TensorFlowNET.Core/Tensorflow.Binding.csproj
#	src/TensorFlowNET.Keras/Datasets/Imdb.cs

feat: implement GRU layer

fix: validate dataset of `Imdb` do not load bug & add: custom `Imdb` path

fix: partially fix the bug of load_model

fix: remove the reflection in the implemention of Bidirectional

fix: add the momentum parameter's implemention of SGD

fix: add the gradient of the tf.gradient opr

feat: add adjust_contrast, adjust_hue, combined_non_max_suppression, crop_and_resize image oprs

fix: revise np.amin, np.amax and add np.argmin

Fix: model.load_weights

feat: add Bidirectional layer

fix: make the initialization of the layer's name correct

fix: ignore the LSTMLoad test

fix: fix the bug of load LSTM model and add test

Thanks for your contribution.