Feature/no slide looping

[barneyb]

if the new loop option is set false, don't loop around from last slide to first (or the reverse), and allow jumping directly to first/last slide using Home/End respectively

[jdan]

Heya @barneyb,

Thanks for this! Sorry for not reviewing sooner. I just made a couple small stylistic comments, but the code looks good to me. Thanks for the README changes too :+1:

[jdan]

Will merge later this afternoon when I'm at my computer, thanks again!