use ~
improve performance

1. make number methods static
2. putLong improve
3. add more benchmark test
improve putRawString
add putBufString benchmark
improve putString
improve getString, getRawString
add test for put buffer string
add test for putString
support auto change save string long to number
fix putLong convert
Merge pull request #5 from node-modules/improve-performance

Improve performance 2X+