Add standard keywords highlight
Squashed commit of the following:

commit 85b72b57cb3078aed028431c295bc9cf5a097a10
Author: QuentinJi <sikuli666@gmail.com>
Date:   Wed Mar 12 23:27:26 2014 +0800

    rename standard library and change colorscheme

commit ed81d29694ea796c6d97bb1f35758a8e53520cbd
Author: QuentinJi <sikuli666@gmail.com>
Date:   Wed Mar 12 22:40:10 2014 +0800

    add support for robot standard keywords