Dragging files and double clicking the playlist doesn't always play music

This issue is not reproducible on Firefox.

This is reproducible in Windows 10 & Chrome/Brave on a website that has a low MEI. This is probably related to https://developer.chrome.com/blog/autoplay/
You can see a website's MEI score by viewing `chrome://media-engagement/`

Personally, I am also able to reproduce this on `webamp.org` because it has a low MEI score.

## Reproduction Steps
- (optional) Open a "Guest" session in Chrome
- Freshly load the website with the Webamp player. Ensure you don't click anywhere
- If no files exist in the playlist, drag one in. (Note: It must be dragged and not added via another button)
- Double click on an item in the playlist
- Verify that the track appears in the Main Window but appears to be stuck at `00:00`; does not play and no audio is playing
- Click anywhere else on the screen and then verify that the music begins the play (Pressing a key also appears to start the music)

In the developer console, the following warning appears:
`The AudioContext was not allowed to start. It must be resumed (or created) after a user gesture on the page. https://goo.gl/7K7WLu`

In Chrome, the easiest way to have no MEI is to [either create a new profile or use a guest window.](https://stackoverflow.com/questions/50683830/reset-chrome-media-engagement-score). Incognito apparently is not sufficient to reset MEI.