Method: Merge user attributes with default attributes.

Method: Retrieve the content of the shortcode

Method: Retrieve a string that can be used for apply_filters() Ensures that all shortcode related filters follow the same naming convention

Method: Output the actual content of the shortcode This is the callback function used by add_shortcode and can also be used programmatically, used in some widgets

Method: Retrieve the actual content of the shortcode

Method: Retrieves an array of default attributes which are automatically merged with the user submitted attributes and passed to $this->get_output()

Method: Retrieves a string used for default content which is used if no content is supplied

Method: Get the singleton instance for the extending class