Add translation system (#85)

migrations/000005.php

@@ -0,0 +1,11 @@
+<?php
+// This migration adds a "language" column to the user table and sets all values to english.
+
+/** @noinspection PhpUndefinedVariableInspection */
+$columnQuery = $db->query("SELECT * FROM pragma_table_info('user') where name='language'");
+$columnRequired = $columnQuery->fetchArray(SQLITE3_ASSOC) === false;
+
+if ($columnRequired) {
+    $db->exec('ALTER TABLE user ADD COLUMN language TEXT DEFAULT "en"');
+    $db->exec('UPDATE user SET language = "en"');
+}