Merge pull request #607 from panjf2000/dev

patch: v2.5.3

patch: v2.5.2 (#600)

patch: v2.5.2

Merge pull request #594 from panjf2000/dev

patch: v2.5.1

With edge-triggered I/O

Merge pull request #574 from panjf2000/dev

patch: v2.4.2

bug: return 0 instead of -1 when error occurred on a write (#569)

Merge pull request #566 from panjf2000/dev

minor: v2.4.0

Merge pull request #550 from panjf2000/dev

patch: v2.3.6

Merge pull request #536 from panjf2000/dev

patch: v2.3.5

Merge pull request #523 from panjf2000/dev

patch: v2.3.4