Corrected SIFT4 + added another test

Author: tdebatty

src/main/java/info/debatty/java/stringsimilarity/experimental/Sift4.java

@@ -138,7 +138,7 @@ class Offset {
                         }
                     }
                 }
-                offset_arr.push(new Offset(c1, c2, is_trans));
+                offset_arr.add(new Offset(c1, c2, is_trans));
 
             } else {
 

src/test/java/info/debatty/java/stringsimilarity/experimental/Sift4Test.java

@@ -46,6 +46,14 @@ public void testDistance() {
         double expResult =  11.0;
         double result = sift4.distance(s1, s2);
         assertEquals(expResult, result, 0.0);
+
+        sift4.setMaxOffset(10);
+        assertEquals(
+                12.0,
+                sift4.distance(
+                        "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
+                        "Amet Lorm ispum dolor sit amet, consetetur adixxxpiscing elit."),
+                0.0);
     }
 
 }