Tooltip: Options not propagated correctly

Tooltip's `enter()` function is not propagating options correctly. In my case I'm using jQuery 1.9.1 while also trying to use the `container` option. However, when the tooltip is displayed the `container` option is lost (reset to the default `false`) resulting in an `insertAfter()` call in `show()` rather than `appendTo()`.

This is a fix that uses jQuery's `$.extend()` to propagate tooltip options.