Feature request: methods to go to the next, previous and specific slide

[gonzedge]

Write some methods so that you can go to the previous slide like this:

$('#slider').ramblingSlider('previousSlide')

To the next slide like this:

$('#slider').ramblingSlider('nextSlide')

And to any specific slide like this:

$('#slider').ramblingSlider('slide', 2)

Also to get the current slide:

$('#slider').ramblingSlider('slide')