Merge pull request shenweichen#86 from shenweichen/dev-din

add din&dien

v0.2.0 (shenweichen#76)

- refactor feature columns.

- Support double precision in metric calculation by setting use_double=True in model.fit()

- Different features can use different embedding_dim

- Add linear part to some models

- Add SequencePoolingLayer

simplify input logic

support multi-value input

add ccpm