implement delta encoder: int
define int decoder base class
impl delta encoding for long
add; ascending sorted delta bitpacking
split blockpack compress algorithms
int input stream
impl CompressStream
impl IntDecompressStream
impl IntDecompressStream
remove redundant comments
union() trial version
impl tests for framework
fix for jdk1.6
encoding filter
IntAscSDBP works anyway
implement intersect()
implement difference()
functionise
fix bug
make interface/class public, for benchmark