Make af.scroller.js pass jshint rule `eqeqeq=true`

Stricter Type comparisons should yield better performance.

Other changes:
- replaced occurences of global `af` as it's injected into the namespace explictly anyway
- some readability reformattings
Removed global af hint (should be obsolete now)
Merge pull request #562 from Philzen/patch-8

Make af.scroller.js pass jshint rule `eqeqeq=true`