Rethethering issue when target element is re-rendered.

[KristiyanHristov]

Actual behavior

When the target element gets removed and added again, the current step stays attached to the last known target position. After scrolling the step gets attached to (0,0). This seems somewhat similar to #95.

Expected behavior

The step should stay attached to the target element even when it gets re-rendered (marionette.js view). It should try to reattach itself to an element with the same selector.

Steps to reproduce

1. start tour (with a step that is attached to an element)
2. remove the element the current step is attached to
3. add the same element (that has the same selector)
4. scroll the page

[KristiyanHristov]

i managed to find a dumb "solution"

var tether = Shepherd.activeTour.getCurrentStep().tether;
var $newTarget = $(tether.options.target).first();
tether.target = $newTarget[0];
tether.position();

[RobbieTheWagner]

This should no longer be an issue, since we moved to popper, but could persist in a different way. Closing for now, in favor of opening a new issue if there are more problems.