Hifiberrydsp

- added config file /etc/sigmatcp.conf
- added notify_on_updated setting in [server] to define an URL that
should be notified on DSP profile changes
- added command_after_startup setting in [server] to define
a command that should be called when the server has started (e.g.
for systemd integration)
- fixed bug in MUTE control
- added LG Sound Sync (experimental)

- implemented simple tone controls (high/low shelf)
- bugfix for get-xml when no DSP profile is available
- bugfix in REW filters

- make sure TCP server starts even if local hostname can't be resolved
- make timeout optional, default will be no timeout
- add more metadata fields
- added optimizer API client

- added timeout to dsptoolkit command line utility

- improved stability when writing to EEPROM
- added more metadata records

- added more REW filters