Add NIST synchronization to enable localization between nodes

[scottveirs]

On occasion we have detected signals from orcas simultaneously on adjacent nodes. This may become more commonplace as we add more hydrophone nodes.

To enable high-precision (<1-10m) localization methods using acoustic data recorded at separate nodes, we will need time synchronization to at least milliseconds and ideally microseconds. (At a speed of 1500m/s and range difference of 1m will result in a time difference of 0.6 milliseconds.)

Proposal:

1. Check to see how the date-time stamp in the FLAC files is acquired currently.
2. Assess other open source tools for time synchronization between nodes
3. Implement a new scheme to synchronize time with NIST and accurately encode the recording start time in the lossless audio data file name.