Anchors - duplicated prefetches

[pavelloz]

Hello,

I inlined your script to make my website faster, but i noticed that it is downloading the page im already in multiple times.
I figured thats because i have internal links (footnotes, headers).

Maybe it would be smart to keep track of urls (without #) and prevent script from firing off duplicated requests.

This is how it looks like:

Other than that great job, it works very nice and is easy to use.