Could it be possible to give float values as input?

[blasco]

Right now we can use as input the "velocity", but I would like it to be between 1 and 2. Would it be possible to update the plugin so it can use a float value?

noremap :call smooth_scroll#up(&scroll, 0, 1)
noremap :call smooth_scroll#down(&scroll, 0, 1)

This would be the ideal case for finer control:

noremap :call smooth_scroll#up(&scroll, 0, 1.3)
noremap :call smooth_scroll#down(&scroll, 0, 1.3)

Any guidance on how this could be achieved would be much appreciated, I could latter create the PR