Add Strings.split
Add aliases QM.isSome and QM.isNone
Fix resolution of content type for parsing response body
Remove QM.isSomething and QM.isNothing for shorter forms
Remove handling of sparse arrays in Arrays.head

- Arrays.firstIndex provides this
Rename QM.firstIndex to QM.first
Rename forEach breakout constant
Add Arrays.clone
Add Arrays.sortWith
Add spec for stable sort in Collections.sortBy
Bump version to 0.4.6