make_request now supports both get and post

server 53 doesn't like it when we post; 82 doesn't seem to mind...
merge get_episode_manifest and get_episode_manifest

Now we can get manifests from server 53. We still can't play streams,
but this is one step closer.

Also, we can accept different vtypes. It's be nice if we can avoid hard
coding the game vtype, but we'll have to find a source.

Progress towards #66
Check for nlds53 streams and show a warning
Add comments, shorten some lines

This makes pylint a bit happier, though still cranky. ;-)