Dual-Pivot Quicksort improvements for highly structured (nearly sorted) arrays and data with small periods

[Alan Bateman]

This one was pushed yesterday but it turns out to have an issue in the 
code that checks if the array is nearly sorted. This can lead to an 
ArrayIndexOutOfBoundsException that isn't caught by the existing tests. 
Vladimir has a fix and we need to extend the sorting test to ensure that 
it hits all the new code. Should have jdk7/tl fixed shortly.

-Alan.