search: fix index bug in the 2d integer-based open list. 	The index was an unsigned int but we need it to be signed 	so that it can store -1.
search: fix index bug in the 2d integer-based open list.
	The index was an unsigned int but we need it to be signed
	so that it can store -1.

eaburns/search,skiesel/search,eaburns/search,eaburns/search,skiesel/search,skiesel/search