Update featherlight.js

The `afterClose` callback is being called at the same time as the fadeOut animation begins.  Moved the call to `afterClose` to the fadeOut completion callback, thereby effectively moving the "event" to when the close is finished.
Merge pull request #59 from quasipickle/patch-1

Call `afterClose` callback after the end of the fadeout.
Release Version 0.4.3