removed doc and code references to magic quotes

- removed all references to magic quotes
- magic quotes are not supported on PHP >= 5.4 (https://secure.php.net/manual/en/security.magicquotes.php)
- Shaarli does not support PHP < 5.5

doc/md/Security.md

@@ -1,9 +1,6 @@
 ## Client browser
 - Shaarli relies on `HTTP_REFERER` for some functions (like redirects and clicking on tags). If you have disabled or masqueraded `HTTP_REFERER` in your browser, some features of Shaarli may not work
 
-## PHP
-- `magic_quotes` is an horrible option of PHP which is often activated on servers. No serious developer should rely on this horror to secure their code against SQL injections. You should disable it (and Shaarli expects this option to be disabled). Nevertheless, I have added code to cope with `magic_quotes` on, so you should not be bothered even on crappy hosts.
-
 ## Server and sessions
 - Directories are protected using `.htaccess` files
 - Forms are protected against XSRF (Cross-site requests forgery):

index.php

@@ -133,15 +133,6 @@
 
 ob_start();  // Output buffering for the page cache.
 
-// In case stupid admin has left magic_quotes enabled in php.ini:
-if (get_magic_quotes_gpc())
-{
-    function stripslashes_deep($value) { $value = is_array($value) ? array_map('stripslashes_deep', $value) : stripslashes($value); return $value; }
-    $_POST = array_map('stripslashes_deep', $_POST);
-    $_GET = array_map('stripslashes_deep', $_GET);
-    $_COOKIE = array_map('stripslashes_deep', $_COOKIE);
-}
-
 // Prevent caching on client side or proxy: (yes, it's ugly)
 header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
 header("Cache-Control: no-store, no-cache, must-revalidate");