refactor:
1) added random.h
2) rename QuickSort1 ==> QuickSort_Median3
3) rename QuickSort2 ==> QuickSort_Median9
3) added cost model for string
refactor: using generalized uninitialized_fill
support count basic operation for string
refactor: added block template to wrapper c arrays.
minor refacotr
support bench string compare
refactor