Experimental refactor.
Now in a working and hopefully much more readable state (as in easier to follow).
- Better snap function
- Fix for disabling buttons when zoomlevels change
- Merge createButton and createZoomButton
- Only refresh when zoomlevels change.
Don't move the knob by fractions of pixels.
Now snapping works again.
Drop some now useless lines of code.
Oops, forgot to move the slider click method
Don't add knob before we have any real zoomlevels.
Add option for knob height. Would love to have this in css but it's a bit hard to calculate it when i want to.
Remove unused images.
I want UNIX line endings.
A very manual cherrypick of an old fix.
Add gitattributes. Hopefully this means no more DOS lineendings
Merge branch 'refactor'

Conflicts:
	src/L.Control.Zoomslider.js