lavd/pulse_audio_common: rename variables and enums

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_common: add context helper functions

Functions allow to connect and disconnect from server.
Helpfull to implement utility functions with nested loops.

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: cosmetics
lavd/pulse_audio_enc: replace simple API with async API

Async API allows to use full capabilites of PulseAudio.

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: add nonblocking mode

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: add buffer fullness messages

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/avdevice: add volume messages

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: implement volume messages

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: implement pause messages

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>