Magellan w/ deep linking doesn't clear the hash when there's no longer an active link

[nvenegas]

How to reproduce this bug:

On a page with with Magellan and data-deep-linking enabled and a top-margin greater than data-threshold (defaults to 50px) such that there is no active link until you scroll past that top-margin:

1. Load the page (without a hash).
2. Scroll down to the first Magellan-tracked element such that the window's location updates to that element's ID (e.g., #first-heading).
3. Scroll back to the very top (e.g., by pressing HOME on your keyboard).

What should happen:

What should happen after each of the steps to reproduce:

1. The window's location should not have a hash.
2. The window's location should have a hash of #first-heading.
3. The window's location should not have a hash.

What happened instead:

What actually happens after each of the steps to reproduce:

1. The window's location does not have a hash.
2. The window's location has a hash of #first-heading.
3. The window's location has a hash of #first-heading.

Browser(s) and Device(s) tested on:

Chrome 63.0.3239.84 on macOS Sierra (10.12.6)

Foundation Version(s) you are using:

6.4.3

[nvenegas]

I'll have a pull request with a fix up shortly!

[nvenegas]

The bug is reproducable in the magellan/active-item.html visual test (via npm run test:visual).