Fix mSpans in StaggeredGridLayoutHelper may be null cause exception.

Avoid use of arrayMap which may cause class cast exception.

Fix layout error when use padding in RangeGridLayoutHelper.

Update version

Update version.

Add listener for sticky status.

Merge pull request #424 from alibaba/feature/performance_massdata

LayoutHelper核心链路性能优化

Merge branch 'develop'

# Conflicts:
#	examples/src/main/java/com/alibaba/android/vlayout/example/VLayoutActivity.java
#	vlayout/src/main/java/com/alibaba/android/vlayout/VirtualLayoutManager.java

Update version

Update version