wip: move BatArray.Cap to BatFullArray (private type)
wip: split BatVect
batFullArray must have a .mliv/.mlv
wip:  add BatFun (combinators that used to be in BatPervasives)
add batteriesLight.mllib
wip: batInternalVect
move the definition of BatResult.t from BatInnerPervasives into BatResult
wip: use split modules