Add 'KeyboardButton' and 'InlineKeyboardButton' objects

src/Entities/InlineKeyboardButton.php

+<?php
+/**
+ * This file is part of the TelegramBot package.
+ *
+ * (c) Avtandil Kikabidze aka LONGMAN <akalongman@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Longman\TelegramBot\Entities;
+
+use Longman\TelegramBot\Exception\TelegramException;
+
+class InlineKeyboardButton extends Entity
+{
+    protected $text;
+    protected $url;
+    protected $callback_data;
+    protected $switch_inline_query;
+
+    public function __construct($data = array())
+    {
+        $this->text = isset($data['text']) ? $data['text'] : null;
+        if (empty($this->text)) {
+            throw new TelegramException('text is empty!');
+        }
+
+        $this->url = isset($data['url']) ? $data['url'] : null;
+        $this->callback_data = isset($data['callback_data']) ? $data['callback_data'] : null;
+        $this->switch_inline_query = isset($data['switch_inline_query']) ? $data['switch_inline_query'] : null;
+
+        if (empty($this->url) && empty($this->callback_data) && empty($this->switch_inline_query)) {
+            throw new TelegramException('You must use at least one of these fields: url, callback_data, switch_inline_query!');
+        }
+
+        /*
+         * @todo check if only one of 'url, callback_data, switch_inline_query' fields is set, documentation states that only one of these can be used
+         */
+    }
+}

src/Entities/KeyboardButton.php

+<?php
+/**
+ * This file is part of the TelegramBot package.
+ *
+ * (c) Avtandil Kikabidze aka LONGMAN <akalongman@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Longman\TelegramBot\Entities;
+
+use Longman\TelegramBot\Exception\TelegramException;
+
+class KeyboardButton extends Entity
+{
+    protected $text;
+    protected $request_contact;
+    protected $request_location;
+
+    public function __construct($data = array())
+    {
+        $this->text = isset($data['text']) ? $data['text'] : null;
+        if (empty($this->text)) {
+            throw new TelegramException('text is empty!');
+        }
+
+        $this->request_contact = isset($data['request_contact']) ? $data['request_contact'] : null;
+        $this->request_location = isset($data['request_location']) ? $data['request_location'] : null;
+    }
+}