Don't replace @ in toAscii

src/Stringy.php

@@ -1747,7 +1747,6 @@ class Stringy implements Countable, IteratorAggregate, ArrayAccess
             'aa'    => ['ع', 'आ', 'آ'],
             'ae'    => ['æ', 'ǽ'],
             'ai'    => ['ऐ'],
-            'at'    => ['@'],
             'ch'    => ['ч', 'ჩ', 'ჭ', 'چ'],
             'dj'    => ['ђ', 'đ'],
             'dz'    => ['џ', 'ძ'],

tests/StringyTest.php

@@ -671,6 +671,7 @@ class StringyTestCase extends PHPUnit_Framework_TestCase
             ['f = z = 3', 'φ = ź = 3'],
             ['perevirka', 'перевірка'],
             ['lysaya gora', 'лысая гора'],
+            ['user@host', 'user@host'],
             ['shchuka', 'щука'],
             ['', '漢字'],
             ['xin chao the gioi', 'xin chào thế giới'],
@@ -1107,6 +1108,7 @@ class StringyTestCase extends PHPUnit_Framework_TestCase
             ['another-foo-bar', 'another..& foo -.-"-...bar'],
             ['foo-dbar', " Foo d'Bar "],
             ['a-string-with-dashes', 'A string-with-dashes'],
+            ['userhost', 'user@host'],
             ['using-strings-like-foo-bar', 'Using strings like fòô bàř'],
             ['numbers-1234', 'numbers 1234'],
             ['perevirka-ryadka', 'перевірка рядка'],