Introduced SuccinctIntIntArrayMap

Introduced an interface for mapping {int -> int[]} in a pseudo-succinct
manner, called SuccinctIntIntArrayMap as well as an initial
implementation called S16SuccinctIntIntArrayMapTest. As it follows from
the name this implementation is backed by Simple16 algorithm, an it
relies on a couple of S16SuccinctIntList, one of each stores keys and
is ordered (and hence is a truly succinct structure) another is
unordered and cannot use the gap encoding, yet it uses Simple16 for
removing redundant bits from stored integers.