Parse the Message Inbound For Emojis

    /**
     * Parse the Message Inbound For Emojis
     *
     * @param string $txt
     * The received message, where to find the Emojis.
     *
     * @param boolean $span
     * If "true", the function will return an html tag
     * Example: <span class="emoji" id="emoji-1F604"></span>
     * this will show the smiling face, require emojisprite.css and emojisprite.jpg
     *
     * Otherwise, if it is "false", return an id. Example, ##1F604##.
     *
     * @return string
     */