Faster OGL sprite sorting algorithm

This patch makes HWR_SortVisSprites faster by replacing selection sort ($O(n^2)

$) with quicksort. ($

O(n \log n)$)

Performance comparison:

Before	After
952 microseconds	114 microseconds
409 microseconds	71 microseconds

changed milestone to %2.2.5

added Enhancement label

merged

mentioned in commit 7317bbb6