title: Display value of :set option
body: <p>If you don't give <code>:colorscheme</code> an argument then it shows the name of the colorscheme that vim is currently using. Is there a similar way in vim to show if an option is set or what the value of the option is set to if it isn't a boolean? For example, if I wanted to know whether <code>autoindent</code> is set or I wanted to know the value of <code>textwidth</code>, how would I find that?</p>