Removing old Firefox-specific code
Unified scrolling on image and slider
Remove more old scrolling code.
Using new fixed html5slider

Fixes Firefox showing the slider at the wrong position, when loading the
page.

See my fork of html5slider.js at https://github.com/MaPePeR/html5slider
Merge pull request #27 from MaPePeR/fix-scroll-on-image

Fix scroll on image and Slider-Firefox-Bug