Support integer return type in array_sort closure

src/main/java/com/laytonsmith/core/functions/ArrayHandling.java

@@ -1826,9 +1826,12 @@ private CArray merge(CArray left, CArray right, CClosure closure, Target t) {
 						} else {
 							value = -1;
 						}
+					} else if(c.isInstanceOf(CInt.TYPE)) {
+						long longVal = ((CInt) c).getInt();
+						value = (longVal > 0 ? 1 : (longVal < 0 ? -1 : 0));
 					} else {
 						throw new CRECastException("The custom closure did not return a value (or returned an invalid"
-								+ " type). It must always return true, false, or null.", t);
+								+ " type). It must always return true, false, null, or an integer.", t);
 					}
 					if(value <= 0) {
 						result.push(left.get(0, t), t);