Added (reverse_)split.
Added (reverse_)split.

Atry/shapeless,roberth/shapeless,milessabin/shapeless,joescii/shapeless,tek/shapeless,triggerNZ/shapeless,malcolmgreaves/shapeless,fthomas/shapeless,wheaties/shapeless,alexarchambault/shapeless,khronnuz/shapeless,TomasMikula/shapeless,notxcain/shapeless,retronym/shapeless,liff/shapeless,lukasz-golebiewski/shapeless,isaka/shapeless,clhodapp/shapeless,lambdista/shapeless