Added check for php calendar extension.

(Its extension is included in the base php package for Linux.
But, It is not included in FreeBSD by default. So, it should be checked.)

pandora_console/install.php

@@ -591,6 +591,7 @@ function install_step2() {
 			$res += check_extension("json","PHP json extension");
 			$res += check_extension("curl","CURL (Client URL Library)");
 			$res += check_extension("filter","PHP filter extension");
+			$res += check_extension("calendar","PHP calendar extension");
 			if (PHP_OS == "FreeBSD") {
 				$res += check_exists ("/usr/local/bin/twopi","Graphviz Binary");
 			}