ls_refresher 0.0.8

A scrollView refresher package.

[0.0.8] - fix: extent of BottomRefresher not performed correctly

[0.0.7] - feat: Support TopOffset For TopRefresher

[0.0.6] - fix: bottomRrfresher not working well on some Android Phone and some situation

[0.0.5] - fix: onRefreshExtent

[0.0.4] - expose const.dart

[0.0.2] - add liscense and guide infomation

       - fixed bugs

[0.0.1] - initialize.