Get API link in Viewer

Currently we can set API link only manually. So, this PR provide some functional that help us get API link directly from Viewer.
And this provide cookie hack that let us get API link without any proxy/VPN!

Code may be looks a ugly but I don't know other workarounds for getting loadFinished-signal from specific frame/iframe (that contains HTML with swf and API data).

Because my english is poor - please check text in settings.
I'm not a fan of this variable name, it doesn't quite convey what it actually is. `langCookie` would be better, or something to that amount - if you see just `lang`, you'd have to scroll up and find its definition to figure out what type it even is.