The loop options of the PacketfileSender was broken.
The pcap filename is open at the creation of the vvPacketSender and close when its delete.
We now create a new vvPacketSender for each send.

On windows the tests were taking minutes instead of seconds. This is because
it's not possible to sleep for a short period of time on this OS.

Until now the tests were only trying to respect the time interval between two
consecutive packets. A packet was send, a sleep was done, etc... But a thread can't
sleep for an exact period of time. It can only sleep for a minimum period of time.
As a result the pcap was send slower than expected on every OS.

After this commit, the tests are only trying to respect the time interval between
the first and the current packets. A sleep is done when the packets are in advance,
otherwise the packet are just send one after each other.

separate the Plugin into:
- LidarPlugin
- VelodyneUiPlugin
- VelodynePlugin

- use wall clock instead of CPU clock (bugfix)
- make the CLI more user friendly

Changes : The ports in the PacketFileSender test are now customizable
Ended : The ports are customizable

The previous design using multiple IOService objects was problematic
to startup and shutdown correctly.

Refactor the code to user a single IOService (and thread) with one
handler per socket.

Additionally make the PacketFileSender send position packets.

For testing purposes its nice to have a sensor stream that runs arbitrarily
long

- add calibration file
- add pcap writing
- add cache / deque
- bug fixes