Add possibility to listen to slide moves outside of slider bounds

[ipapps]

It can be difficult to let the finger exactly on the circle of the slider. For a better user experience, it can be useful to let the sliding and animation continue as long as the user touches down the slider, even if its finger is outside the bounds of the slider.
This pull request adds a boolean (which defaults to the previous behaviour) to allow the developer to add this feature.

[tony-ditchlabs]

Didn't see this, just wrote something similar and submitted a PR.
Instead of using a bool to just turn it on/off entirely like you did, I edited the 25.0 minimum width to be an argument so, you can set the fault tolerance to any value.