Parse "ts" timestamp as the creation date of the Darwin message

[vladvelici]

pPort.ts is the creation time of the Darwin message. It's useful to keep track of this to avoid applying older "updates" or duplicated messages. Also to keep a history of when events happened in the future.

Also find where this is documented, if anywhere, as I only found out about it from forum messages on
https://groups.google.com/forum/#!topic/openraildata-talk/5RUyLuzXwic which is a bit vague.