Audio Recording Tab 0.2.0

New
- Save a whole track without listening to it. Supports direct audio files.
- Players with no playlist: the track is collected as the player loads it,
with an option to save what has been collected so far.
- New setting "Ignore site volume and mute" (on by default): records at full
level even when the site's player volume is turned down or the tab is muted.
- Several tabs can be recorded at the same time.
- Silence warning: if a player is playing but no sound reaches the recording
for 7 seconds, the add-on tells you and suggests recording through a
virtual audio input (e.g. BlackHole).
- Works without the toolbar button: an icon in the address bar (shown only on
tabs with sound, can be turned off), keyboard shortcuts (Alt+Shift+S save
the whole track, Alt+Shift+O open the window) and a settings page where the
shortcuts can be changed.

Improved
- Recordings start at the first sound instead of at the button press.
Recordings with no sound at all are still saved in full.
- Saves the track that is actually playing, not the next one the site
preloads in its queue.
- File name and tags come from the player's track info (Artist - Title)
when the site provides it.
- MP3 tags: Artist and Title come from the file name template or the cleaned
tab title; the site domain is no longer written into the tags.
- Protected (DRM) tracks are detected right away. If the page has also loaded
an unprotected version of the same track, that version is saved.