Expose additional metadata

[rajlaud]

Contribution from Greg X:

• Expose audio encoding details such as media type, bit rate, etc
• Expose LMS remote and remote_title fields for improved identification of internet radio stations
• Allow retrieval of elapsed time and total time with floating precision
• Allow caller to specify LMS tags to request additional information from the server

[rajlaud]

Added logic to force the playlist to update if seeking additional tags. If no additional tags, normal playlist logic remains (only fetch on change).