Switch from using two-way binding for rzSliderOptions to using expression binding. Using expression
binding enables more complex use cases such as using the return value of a function as an options
object.

Closes #265.

Simplified expression that was potentially unsafe for minification

The final goal is to split tests in several files

feat(pointerColor): Adding feature for dynamic pointer color.

Changing the color of the pointer of a slider based on the value. Just pass a function to the
'pointerColor' option which returns a valid CSS color definition (either hex or named) and let the
pointer shine in the brightest colors

feat(translate): Pass a label string as third arg to the translate function to differentiate the lab

Closes #252

Thanks to this, we can now pass html-formated content in the translate function

Closes #251

Closes #245

feat(enforceStep): Add an enforceStep option (defaults to true)

feat(selectionBar): Add a showSelectionBarFromValue

feat(range): Add a noSwitching value to prevent switching min/max

I was not accepting sliders with floor=7, ceil=7 and step=10 that are actually valid.

Closes #234

The minimum range authorized on the slider.

Closes #231

onStart should be called before any update so it should not be wrapped inside a .

perf(initialisation): Remove the timeout call in init.

Closes #220