Features

• Add more of characters to the non-recommended list of feature name characters.
• Make the inference op multi-thread compatible.
• Print an explicit error and some instructions when training a model with a Pandas dataframe.
• pd_dataframe_to_tf_dataset can automatically rename feature to make them compatible with SavedModel export signatures.
• model.save(...) can override an existing model.
• The link function of GBT model can be removed. For example, a binary classification GBT model trained with apply_link_function=False will output logits.