BUG: When manual: true AND mouseOnToPopup: true

When configured for `{ manual: true}` and `{mouseOnToPopup: true}` I was experiencing this:

* mouse on the tooltip, then mouse off and it hides.

Seems to me that when in manual mode, mousing on and off the tooltip should not hide it.

Thanks for building this library, it's my favorite tooltip lib! 

Cheers! :beers: