function references in hyperx need to look like:
```
onloadedmetadata=${onLoadedMetadata}
```
and not:
```
onloadedmetadata="${onLoadedMetadata}"
```
also removed some unnecessary `torrent.ready` checks in the player.
No header on Linux and OSX, just a back button on mouseover
ESC exits fullscreen, or if already not in fullscreen, goes back
More accurate scrub position
Removed the calc(100% -38x) hack, replaced with flexbox
As of this PR (https://github.com/substack/hyperx/pull/22) to hyperx,
attributes are automatically converted to properties for the few cases
where they’re different: class, for, and http-equiv.
