AVnu/Open-AVB — pull request #74 by masche842 (2014-06-20 08:52:46+00:00)
Title: Make sure calculated Timestamps have a valid version

See #73, it's the right branch now.

When using addition and substraction operators on Timestamp instances
no version has been assigned.
Because of this syntonization was not working.
This commit introduces a new constructor taking a version argument
and changes + and - functions to use it.