URL checking improved

When adding the scheme to an URL use correct scheme (http or https) and port.
Checking for "http" or "https" via strstr() in the URL matched also these strings embedded in the URL (e.g. in /static/http/index.html), due to that checks changed to strpos().

components/com_wrapper/views/wrapper/view.html.php

@@ -80,18 +80,20 @@ public function display($tpl = null)
 
 		if ($params->def('add_scheme', 1))
 		{
-			// Adds 'http://' if none is set
+			// Adds 'http://' or 'https://' if none is set
 			if (substr($url, 0, 1) == '/')
 			{
-				// Relative url in component. Use server http_host.
-				$wrapper->url = 'http://' . $_SERVER['HTTP_HOST'] . $url;
+				// Relative url in component. Use scheme + host + port.
+				$wrapper->url = JUri::getInstance()->toString(array('scheme', 'host', 'port')) . $url;
 			}
-			elseif (!strstr($url, 'http') && !strstr($url, 'https'))
+			elseif (strpos($url, 'http://') !== 0 && strpos($url, 'https://') !== 0)
 			{
+				// Url doesn't start with either 'http://' or 'https://'. Add 'http://'.
 				$wrapper->url = 'http://' . $url;
 			}
 			else
 			{
+				// Url starts with either 'http://' or 'https://'. Do not change it.
 				$wrapper->url = $url;
 			}
 		}