module functions for Vector<Vector<'T>>

flatten : Vector<Vector<'T>> -> seq<'T>
nthNth : int -> int -> Vector<Vector<'T>> -> 'T
tryNthNth : int -> int -> Vector<Vector<'T>> -> 'T option
singleton : 'T -> Vector<'T>
updateNth : int -> int -> 'T -> Vector<Vector<'T>> -> Vector<Vector<'T>>
tryUpdateNth : int -> int -> 'T -> Vector<Vector<'T>>
windowSeq : int  -> seq<'T> -> Vector<Vector<'T>>
Merge pull request #250 from jackfoxy/master

module functions for Vector<Vector<'T>>