Slider fixes and enhancements.

- follows HTML5.1 input range specification as it possible.
- handles input/change events

Fixes #10 Slider: add missing intern tests (unit + functional)
Fixes #32 Slider: the 'disable' state should have an associated style
Fixes #90 Slider: unable to change width
Fixes #30 Slider: properties must be dynamic as much as possible
Fixes #29 Slider: a way to translate the range interactively
Fixes #130: Slider: use templates
Fixes #131