This removes the use of AGC's experimental atomic bool controls in
favor of the already stable periodic_access method of control.
The disadvantage is that periodic_access is significantly more difficult
for most users to undestand. It requires understanding of how closures
work with ownership and threading primitives like Atomics & Arc.
This example plays a C Major 6th chord by adding four sources, sine waves frequencies of C, E, G, and A, to a `DynamicMixerController`, and appends its respective `DynamicMixer` to a sink.
As I understand it, this is the issue:
* Previously, when a queue has `keep_alive_if_empty` set to true, and it becomes empty, then it will push a silence lasting 10ms onto the queue.
* This is an issue because `current_frame_len` would have returned the worst case, `512`, and the silence lasts less than that.
* This means that unless the source is added immediately to the queue, and so a silence is never played, then the first actual source could start playing at a frame that is not aligned to its channels, or play at the wrong sample rate.
* This is only determined by when the source is added to the queue after its initialization. This explains why the issue was inconsistent, as it relied on the speed of execution of code which is basically random.
Solution
* Change the functionality of `Zero` to add a method to create a silence with a certain number of frames.
* Replace the 10ms silence with a silence the length of `THRESHOLD`
* Change queue's `current_frame_len` to return `THRESHOLD` if a silence will be played next.
* add symphonia decoder
* add symphonia-flac
* better compile errors
* remove unsafe send
* update ci
* sudo
* disable duration check because symphonia does not support it
* add error handling
* cleanup
* update symphonia and fix breaking changes
* update to published symphonia version
* update docs
* reduce namespace duplication
* remove extra reference to current frame
* pr comments
* exclude decoders from module if unused
* fix flac test
* recommend disabling default features with symphonia
