Squeezebox: Add Player State to Speech Commands. Fixes #1474 #1481

Added the current playlist track, timestamp, repeat/shuffle modes for
current player playlist.
Changed the "squeezeboxSpeak" function to an additive mode for speech
playback and add restoration of previous playlist item and time.
Added a new parameter to
"squeezeboxSpeak(playerId,message,volume,resumePlayback)" which allows
for speech commands to override playback resume (item state is still
restored however player will be paused after speech completes). Useful
for Doorbell type workflows.