修复 2.1.8 展示 bug，发布 2.1.9

support sorting (hyj1991#26)

update document & prepare for v2.1.6

release v2.1.5

update the document of v2.1.3

optimized documentation

remove temporary to tag v2.1.1

tag to release v2.1.0

tag to release v2.0.11

tag to release v2.0.9