Warn about PulseAudio in the doc and rework related sections

[pushfoo]

Changes

1. Document the PulseAudio bug (Pulse Audio Exception - Hard to Reproduce #952)
2. Add "Choosing audio drivers" heading
3. %s/Pulseaudio/PulseAudio/g and rename the Pulse heading to PulseAudio for consistency
4. Expand the PulseAudio section with better pros / cons + bug
5. Expand the OpenAL section with Linux install command examples and other info
6. Add link targets for relevant headings
7. Rearrange + add table footnotes for cleanliness
8. Link the new doc from the quickstart
9. Link the doc from pyglet/__init__.pys doc for the options['audio'] key

[caffeinepills]

Personally I am not agreeing with some of the language, and there are some errors:

Calling the PulseAudio buggy implies it's unusable. I think just putting warnings of it may having issues with those 2 issues you mentioned. We've only had one report about such issues and could be system, version, or something else going on.

The 'default' section on audio is incorrect, it says it is: ('openal', 'pulse', 'xaudio2', 'directsound', 'silent') but that was just an example to show how to re-arrange the order. The default is actually ('xaudio2', 'directsound', 'openal', 'pulse', 'silent')

Pyglet does not technically consider OpenAL 'preferred', and the language implies people should install it on their platforms. That should be up to the developer if they wish their users to use OpenAL on all platforms.

The default behavior of Pyglet is just so that sound just works on all OS platforms as much as possible, it will go through all drivers until it finds one. OpenAL should be recommended over PulseAudio simply because of positional audio. However, Windows has XAudio2 (and DirectSound) backends which is more feature complete than OpenAL.

My 2c.

[pushfoo]

@caffeinepills I think I got everything you and Ben mentioned. PulseAudio is now described as limited rather than broken.