Revert "Merge pull request #105 from FraGoTe/patch-1"

This reverts commit 1fbb4fd, reversing
changes made to 95c9386.

The revert was performed as it introduced an infinite loop in the
`BarcodeTest::testCODE128()` test case.

Conflicts:
	src/Barcode/Code128.php

src/Barcode/Code128.php

@@ -180,10 +180,7 @@ public function hasValidCharacters($value)
                     break;
             }
 
-            if (! empty($value) && strlen($value) > 1) {
-                $value = $strWrapper->substr($value, 1, null);
-            }
-
+            $value = $strWrapper->substr($value, 1, null);
             $read  = $set;
         }