Add custom load more item feature, and fix some issues.

Merge pull request #9 from showang/dev

[Release v1.1.0] Refactoring section title features, and improve some performance.

Merge pull request #8 from showang/dev

[v1.0.2] Fix section title strategy issue

Merge pull request #6 from showang/dev

[Release v1.0.1]Downgrade and remove some libraries to reduce some build limitations.

Merge pull request #5 from showang/dev

[Release v1.0.0] Refactoring for more use cases and improve performance.

Merge pull request #4 from showang/dev

Fix the issue of notifyGroupDataChanged which notify wrong index of r…

Merge pull request #3 from showang/dev

Update kotlin, androidx libraries version. Increase version number.

Add some functions for operate data group. And add coroutine support.

Merge pull request #1 from showang/dev

Add load more error state. Fix footer bug when no data exist.

Code coverage support