new quicksort, v1
removed ;
small bug fixed for returning Nothing when the array is size 0.
implemented changes for performance gains suggested by kmsquire
v2 after implementing changes suggested by kmsquire
changed style of the inner loop to single lined while loops to comply with previous styles
a v3 median-of-three quicksort with a bug fix in the swapping to create the median, and removal of the unnecessary placing-the-pivot-in-the-hi-spot.
small style change to reflect the original. getting changes made to nans2end, rebenchmarking