openhab#11272)

The binding requires a parameter to activate the parsing of sink-input entries on the pulseaudio server. This patch :
- document this behaviour
- fix the parsing of these parameters if a configuration file is used (the old method of casting launched a class cast exception)

Other small improvements :
- Force a refresh/new parsing when the configuration changes
- Fix scheduled disconnection : if a sound is played during the grace period, the scheduled disconnection is postponed, not added to the last
- add a possibility to never disconnect the audio sink (in order to have a lower latency when playing sound)
Closes openhab#11272

Signed-off-by: Gwendal Roulleau <gwendal.roulleau@gmail.com>

Signed-off-by: Gwendal Roulleau <gwendal.roulleau@gmail.com>