FIX: change NeighborId type for UNIX (long int)

include/grmNeighborhood.h

@@ -23,7 +23,7 @@
 #if defined(_WIN32)
 typedef __int64 NeighIDType;
 #else
-typedef long unsigned int NeighIDType;
+typedef long int NeighIDType;
 #endif
 
 enum CONNECTIVITY{FOUR = 0, EIGHT};