New get_fetcher() API returning RtmpFetcher and HdsFetcher classes
Add “iview_{version}.swf” URL for Akamai HD player verification
Merge commit 'github/livestreamer~1' into HEAD
Simplify awkward str.split() and str.join() manipulations

* No longer removes full stops (.) from subtitles URLs
Separate load_script() function
Use name of substituted object by default
Test for live stream without “url” key
Fall back for “url” (n) key; distinguish live stream as absolute RTMP URL

This way we can handle a missing “url” key, and a relative file name in the
“livestreamer” (r) key is handled just like a “url” value.