Make mbstring extension optional

We're using Symfony polyfill now to be in line with phpMyAdmin.

Signed-off-by: Michal Čihař <[email protected]>

Author: nijel

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+* Make mbstring extension optional (though Symfony polyfill).
+
 ## [4.2.2] - 2017-09-28
 
 * Added support for binding parameters.

composer.json

@@ -17,7 +17,7 @@
     },
     "require": {
         "php": ">=5.3.0",
-        "ext-mbstring": "*"
+        "symfony/polyfill-mbstring": "^1.3"
     },
     "require-dev": {
         "phpunit/php-code-coverage": "*",
@@ -27,6 +27,7 @@
         "phpmyadmin/motranslator": "<3.0"
     },
     "suggest": {
+        "ext-mbstring": "For best performance",
         "phpmyadmin/motranslator": "Translate messages to your favorite locale"
     },
     "bin": [