Known bugs
----------
Multiple audio tracks cannot be mixed in realtime.

Fix required:
on the 1.0 TODO list



Foreground and background generators cannot be mixed.

Fix required: on the 1.0 TODO list.









When playing an audio-only clip, a generator can be started in the
background (if a transition is on). Stopping playback and then
restarting without clearing the effects can cause a crash.

Fix required:
prevent transitions from being activated during playback of audio-only clips.




Ping-pong loop works badly with single images, especially at higher frame rates.
Workaround: switch off ping-pong looping for single images.

Fix required: try to optimise for single image clips, so we are not constantly 
reloading them.





