Rewrote split interstitial detector:
Rewrote split interstitial detector:

 - sorts vacancies and interstitials into groups using cluster filter
 - defines split int as a group containing 2 ints and 1 vac only

chrisdjscott/Atoman,chrisdjscott/Atoman,chrisdjscott/Atoman,chrisdjscott/Atoman,chrisdjscott/Atoman