Mishmash of smallish fixes, enhancements, and cleanups

Includes various bug fixes, enhancements, and cleanups, including:

- moves `ktkGetNextDate` out of the global namespace
- removes stray alert + accidental click handler corruption
- fixes `dateDeserialize` to allow dates before 1970 (and looser date formats)
- fixes #52 (`scrollToToday` option)
- fixes & robustifies cross-browser mouse wheel detection
- adds check for `$.cookie` if `useCookie` option set to `true`
- optimizes PNGs (via smush.it)
- updates jshint options
- points out some unused variables (for future cleanup efforts)

(Goes without saying, please test this before accepting. ;)