Accept nonstandard links

Issue
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Currently skrollr-menu will not animate / deal with any hashlinks to the current page unless they are expressed with `href='#xxx'`. This means that absolute links to the current page with hash-links will fail when clicked from that page. 

Example
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The menu of a site has a link with `href='/#mysection'`. This will fail because the preceding `/` causes skrollr-menu not to parse it, even though it should be considered a valid link. 

Changes
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This commit addresses this by including a function to check if a link points to the current page, and also supports any GET parameters that a clicked hash-link may have. 
Best I can do in terms of code simplification I think. `link.hash` still includes any GET parameters so I've trimmed them off. I know that Regex can be opaque but here I think it's necessary and I've reduced its role to a minimum.