feat: add new differOption: lengthLimit

Previously this is hard-coded as 1000 in https://github.com/jfcherng/php-sequence-matcher/blob/5de2243aa611a66395d85ba1a9169b439bd13e4d/src/SequenceMatcher.php#LL683C28-L683C32

Fixes #71

Signed-off-by: Jack Cherng <jfcherng@gmail.com>

Author: jfcherng

README.md

@@ -82,6 +82,8 @@ $differOptions = [
     'ignoreLineEnding' => false,
     // ignore whitespace difference
     'ignoreWhitespace' => false,
+    // if the input sequence is too long, it will just gives up (especially for char-level diff)
+    'lengthLimit' => 2000,
 ];
 
 // the renderer class options

example/demo_base.php

@@ -24,6 +24,8 @@
     'ignoreLineEnding' => false,
     // ignore whitespace difference
     'ignoreWhitespace' => false,
+    // if the input sequence is too long, it will just gives up (especially for char-level diff)
+    'lengthLimit' => 2000,
 ];
 
 // options for renderer class

src/Differ.php

@@ -111,6 +111,8 @@ final class Differ
         'ignoreLineEnding' => false,
         // ignore whitespace difference
         'ignoreWhitespace' => false,
+        // if the input sequence is too long, it will just gives up (especially for char-level diff)
+        'lengthLimit' => 2000,
     ];
 
     /**