Add support for specifying URL to load in URL

[lucaswerkmeister]

It would be cool if you could specify a URL to load via http://app.rawgraphs.io/?url=URL, e. g. like this%2520WHERE%2520%257B%2520%2520%253Fsub%2520wdt%253AP509%2520%253Fy.%2520%2520%253Fsub%2520wdt%253AP31%2520%253Fid.%2520%257D%2520GROUP%2520BY%2520%253Fid%2520%2522%257D%2520%257D%2520%257D%250ASELECT%2520%253Fcid%2520%253Fcause%2520(COUNT(*)%2520AS%2520%253Fcount)%2520WHERE%2520%257B%250A%2520%2520BIND(wd%253AQ5%2520AS%2520%253Fthing)%250A%2520%2520%253Fpid%2520wdt%253AP31%2520%253Fthing.%250A%2520%2520%253Fpid%2520wdt%253AP509%2520%253Fcid.%250A%2520%2520OPTIONAL%2520%257B%250A%2520%2520%2520%2520%253Fcid%2520rdfs%253Alabel%2520%253Fcause.%250A%2520%2520%2520%2520FILTER((LANG(%253Fcause))%2520%253D%2520%2522en%2522)%250A%2520%2520%257D%250A%257D%250AGROUP%2520BY%2520%253Fcid%2520%253Fcause%250AORDER%2520BY%2520DESC(%253Fcount)%2520%253Fcause). This feature was showcased in this tweet, and Wikidata Query Service support is pending in this change, but this doesn’t yet seem to be available on the main website, and I couldn’t find any commits, issues or pull requests related to it.

[poVoq]

cool would be also Odata support

[ysykzheng]

please see #176