Add multi-eci decoding for PDF417 (#1507)

* - Added multi-eci decoding for PDF417
- Fixed issue that some multi-eci encoded PDF417 codes were missing ECIs

* Syntactic changes

* - Fixed issue that ECIs were not processed correctly in all allowed locations in binary encoded data as specified in section 5.5.3.2 of the spec
- Added verifying unit test

core/src/main/java/com/google/zxing/common/MinimalECIInput.java

@@ -208,6 +208,27 @@ public int getECIValue(int index) {
     return bytes[index] - 256;
   }
 
+  @Override
+  public String toString() {
+    StringBuilder result = new StringBuilder();
+    for (int i = 0; i < length(); i++) {
+      if (i > 0) {
+        result.append(", ");
+      }
+      if (isECI(i)) {
+        result.append("ECI(");
+        result.append(getECIValue(i));
+        result.append(')');
+      } else if (charAt(i) < 128) {
+        result.append('\'');
+        result.append(charAt(i));
+        result.append('\'');
+      } else {
+        result.append((int) charAt(i));
+      }
+    }
+    return result.toString();
+  }
   static void addEdge(InputEdge[][] edges, int to, InputEdge edge) {
     if (edges[to][edge.encoderIndex] == null ||
         edges[to][edge.encoderIndex].cachedTotalSize > edge.cachedTotalSize) {