add utils
add double number system.
use util to make code pretty
add util - max in varargs
add set utils
introduce queue
add util - iterator of varargs. and applied
extract a class from FilteredIterable
rename and fix assertion bug
add a util - int bijection
improve speed of map
add util for map
add open addressing hash table
add undirected graph data structures
Merge branch 'master' of https://github.com/psjava/psjava.git