Merge pull request #1232 from d2l-ai/master

2.0.0版发布

Merge pull request #1182 from d2l-ai/master

Release 2.0.0-beta1

Merge pull request #1039 from d2l-ai/master

Release v2.0.0-beta0

Merge pull request #913 from d2l-ai/master

2.0.0-alpha2 hotfix

Merge pull request #803 from d2l-ai/master

v2.0.0-alpha1 release

Merge pull request #686 from d2l-ai/master

v2.0.0-alpha0

[1.0.0] release

add back build env

rnn and backprop fix

Merge pull request #213 from astonzhang/nin

consistent indentation