Merge pull request #223 from didi/transfer

Transfer learning

Merge pull request #200 from didi/solver_utils_fix

fix solver utils bugs

Merge pull request #176 from didi/release_notes

*add release_notes

Merge pull request #145 from didi/zh794390558-patch-1

Update install-delta.sh

Merge pull request #145 from didi/zh794390558-patch-1

Update install-delta.sh

Update README.md

add models, benchmark, etc