Update pnotify.core.js

The mouseleave event which is setup to reset the timer doesn't catch the close click. If you click close and quickly move the cursor out the close button hides but the message is still present until the timer runs out. Add a check to see if the message is not animating to restart the timer.
Merge branch 'master' of https://github.com/Medros/pnotify into Medros-master
Fixed animating check.

Fixes #124. Fixes #132. Fixes #142.

All credit to @Medros for figuring out the solution to this fucking bug that has been around for literally years!
Merge branch 'Medros-master'