Enable parsing of VLAN-tagged packages

If ethertype is 0x8100 also check dot1q type for 0x22f0.

Signed-off-by: Schettke, Marc <schettke@ms2.info>
Merge pull request #76 from masche842/vlan-fix

Enable parsing of VLAN-tagged packages in avtp_astimes.py
Fixed Timestamp class to propagate version information
Merge pull request #61 from christopher-s-hall/open-avb-next

fix and use Timestamp version field
Fixed problem where local network clock to system clock offset was incorrectly computed.
Merge pull request #79 from christopher-s-hall/open-avb-next

Fixed network-system clock offset computation
Removed support for 1 step clocks - these are not allowed on 802.1AS nodes
Fixed shared memory issues on Linux:
* If default group doesn't exist, tries root instead
* Doesn't fail if unable to set ownership
* Sets shared attribute on mutex in shared memory
Merge pull request #80 from christopher-s-hall/open-avb-next

Misc Changes