Various fixes & cleanup

Included changes:
- moves `ktkGetNextDate` out of the global namespace
- removes stray alert + accidental click handler corruption
- fixes `dateDeserialize` to allow dates before 1970
- updates jshint options
"Smushed" (optimized) PNGs
adds check for `$.cookie` if `useCookie` option set to `true`
Improved mouse wheel detection

Better cross-browser mouse wheel event binding.
(Also points out some unused variables for later cleanup purposes..)
Fixes taitems/jQuery.Gantt#52 (`scrollToToday`).
missed minified file