Slider: Support for a range-theme

[hpbuniat]

I added a third theme to the ui.slider to highlight the part between slider-start and the current handle, like the jquery-ui slider does.

[v00d00j3st3r]

+1

[johnbender]

@hpbuniat

Looks super nice (especially the the test :D), any chance you can resubmit this without the extra merge commits? Ie, new branch and cherry pick the single relevant commit.

@toddparker

Is this something we want to support from a usability perspective?

[toddparker]

I was just saying that I wanted to add this as an option at some point so this is fantastic. Just confirming - this feature is activated by adding the rangeTheme to the input, right? Does this add anything else to the API?

In terms of docs, I'd like to leave the first slider alone because it is meant to show the default slider. We can add this as another demo below. This new data- attr needs to be documented here:
http://jquerymobile.com/test/docs/api/data-attributes.html

[hpbuniat]

@johnbender
I'll move this to a new branch, to get rid of those extra commits.

@toddparker
Right, this is activated via the range-theme attribute. Of course the theme must contain a corresponding css-class. When creating the new branch, i'll cleanup the docs in one go.

[johnbender]

@hpbuniat

Alright, I'm going to close this pull request in expectation of your update.