Stopping right after you press play in notifications no longer starts playback

Changes

• If you pressed stop while the metronome was still getting ready to play (loading sounds and so on), it started playing once it was ready. This was more likely when getting ready took longer, such as the first play after opening the page.
• If you press stop while it's getting ready, it now stays stopped without playing. The notifications and lock screen also go back to showing it as stopped.
• The "Lock screen and notifications" section of the manual now explains what to do when Metronome.fm still shows in your notifications after you've left it stopped and used other apps for a long time, but nothing plays when you tap play.