Merge pull request d2l-ai#1314 from d2l-ai/master

Release 0.14.3

Merge pull request d2l-ai#1278 from d2l-ai/master

 Release 0.14.2

Merge pull request d2l-ai#1213 from d2l-ai/master

fix frontpage link

Merge pull request d2l-ai#1099 from d2l-ai/master

Fix TF Googlenet and Densenet accuracies

Update config.ini

0.7.1

Update preface.md

add back build env