Deprecate CI_Input::is_cli_request() and add common function is_cli() to replace it

Calls to this function are often needed before the Input library is available
diff --git a/user_guide_src/source/helpers/date_helper.rst b/user_guide_src/source/helpers/date_helper.rst
index 5dfee8b..8126eba 100644
--- a/user_guide_src/source/helpers/date_helper.rst
+++ b/user_guide_src/source/helpers/date_helper.rst
@@ -80,7 +80,7 @@
 	$time = time();
 	echo standard_date($format, $time);
 
-.. note:: This function is DEPRECATED.Use the native ``date()`` combined with
+.. note:: This function is DEPRECATED. Use the native ``date()`` combined with
 	`DateTime's format constants
 	<http://www.php.net/manual/en/class.datetime.php#datetime.constants.types>`_
 	instead: