Merge pull request #682 from panjf2000/dev

patch: v2.7.2

Merge pull request #671 from panjf2000/dev

patch: v2.7.1

Merge pull request #668 from panjf2000/dev

minor: v2.7.0

Merge pull request #664 from panjf2000/dev

patch: v2.6.3

Merge pull request #661 from panjf2000/dev

patch: v2.6.2

Merge pull request #658 from panjf2000/dev

patch: v2.6.1

Merge pull request #651 from panjf2000/dev

minor: v2.6.0

Merge pull request #641 from panjf2000/dev

patch: v2.5.9

Merge pull request #639 from panjf2000/dev

patch: v2.5.8

Merge pull request #625 from panjf2000/dev

patch: v2.5.7