Update of Dual-Pivot Quicksort, Sorting and Arrays classes

[Vladimir Iaroslavski]

Hello!

I've updated Dual-Pivot Quicksort, Sorting and Arrays classes,
please review.

http://cr.openjdk.java.net/~alanb/6976036/webrev

In compare with previous version (JDK 7 vs. JDK 6) the ratio is:
52.14% for client and 41.62% for server VM (was 57.22% and 46.18%).

Summary of changes:

1. Range check was moved from DualPivotQuicksort to Arrays class.
2. Pair insertion sort is used for sorting small arrays instead of traditional.
3. Added new test in Sorting class: compare with insertion sort on small arrays.
4. Minor cosmetic changes.

Thank you,
Vladimir