support ARABIC TATWEEL.

Signed-off-by: Anas Altair <anastr244@gmail.com>

@@ -4,6 +4,7 @@
 
 - Fix mixing Arabic with English [Anas Altair]
 - Support Dagger alif in Arabic [Anas Altair]
+- Support ARABIC TATWEEL [Anas Altair]
 
 ## 1.10.1
 

@@ -25,6 +25,8 @@ class PdfArabic {
   /// Arabic shape substitutions: char code => (isolated, final, initial, medial).
   /// Arabic Substition A
   static const Map<int, dynamic> _arabicSubstitionA = <int, dynamic>{
+    0x0640: <int>[0x0640, 0x0640, 0x0640, 0x0640], // ARABIC TATWEEL
+
     0x0621: <int>[0xFE80], // ARABIC LETTER HAMZA
     0x0622: <int>[0xFE81, 0xFE82], // ARABIC LETTER ALEF WITH MADDA ABOVE
     0x0623: <int>[0xFE83, 0xFE84], // ARABIC LETTER ALEF WITH HAMZA ABOVE

@@ -86,7 +86,7 @@ void main() {
         1614,
         65227
       ]),
-      ArabicText('اللغة العربيَّة هي أكثرُ اللغاتِ', <int>[
+      ArabicText('الــلغـة العــربيَّة هي أكثرُ اللغاتِ', <int>[
         65172,
         65232,
         65248,