Tweak description
__FILE__ symlink workaround, trac ticket #16953
Fix the __FILE__ fix with an ugly fix

The $plugin variable is not a full path on activation, so the require below fails and causes a fatal error. This mess should hopefully only be temporary.
Add filter for default thumbnail size
Tweak package tags
Change how options and initialization is done

The JavaScript options are printed separately as a global object and the
lightbox is initialized on DOM ready instead of right away, so
manipulation of said object works from that event.
Update version to 2.2.0. Update documentation.