Implemented checkChildrenOnGroupCheck logic in CheckStateStore. Started implementing checked item counts which is also delegated to CheckStateStore.
Implemented some of the checked item getters in CheckStateStore (MultiList delegates to it). Added an array concat and a LongSparseArray helper in Util.
Finished final CheckStateStore TODOs and fleshed out all MultiCheckable methods in the list.Time to start debugging *fingers crossed*
One line delete to fix nullpointer
Merge pull request #4 from kemallette/choice_modes

At this this point, checking is working visually for groups and children for choice mode multi (with stableIds). I haven't played with any others yet.