skip, limit and slice

[Remi Forax]

skip and limit can be written using slice(),
   limit(n) => slice(0, n)
   skip(n) => slice(n, Long.MAX_VALUE)

so there are not strictly needed.
Given that limit() is a known idiom, may be only limit() and skip() 
should be kept with the default implementation of limit() calling 
slice(0, limit).

cheers,
Rémi