used PHP 7.1 features

Author: dg

src/Mail/Message.php

@@ -431,7 +431,7 @@ protected function buildText($html)
 	private function getRandomId()
 	{
 		return '<' . Nette\Utils\Random::generate() . '@'
-			. preg_replace('#[^\w.-]+#', '', isset($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : php_uname('n'))
+			. preg_replace('#[^\w.-]+#', '', $_SERVER['HTTP_HOST'] ?? php_uname('n'))
 			. '>';
 	}
 

src/Mail/MimePart.php

@@ -96,7 +96,7 @@ public function setHeader($name, $value, $append = FALSE)
 	 */
 	public function getHeader($name)
 	{
-		return isset($this->headers[$name]) ? $this->headers[$name] : NULL;
+		return $this->headers[$name] ?? NULL;
 	}
 
 

src/Mail/SmtpMailer.php

@@ -56,9 +56,9 @@ public function __construct(array $options = [])
 			$this->host = ini_get('SMTP');
 			$this->port = (int) ini_get('smtp_port');
 		}
-		$this->username = isset($options['username']) ? $options['username'] : '';
-		$this->password = isset($options['password']) ? $options['password'] : '';
-		$this->secure = isset($options['secure']) ? $options['secure'] : '';
+		$this->username = $options['username'] ?? '';
+		$this->password = $options['password'] ?? '';
+		$this->secure = $options['secure'] ?? '';
 		$this->timeout = isset($options['timeout']) ? (int) $options['timeout'] : 20;
 		$this->context = isset($options['context']) ? stream_context_create($options['context']) : stream_context_get_default();
 		if (!$this->port) {