String version parsing

The Version class now has a new constructor that accepts a String
Fixed uninitialized tube contents bytes

ArtemisPlayer.setTubeContentsValue() now accepts any byte for the value
argument. This is to avoid throwing an exception when the server sends
an uninitialized byte for this value (as it will sometimes do when the
tube state field indicates the tube is empty).
Removed unused imports

Accidentally left some imports in when I was testing something
vesselData.xml parsing

ArtClientLib can now parse vesselData.xml and provide any information in
it. If you invoke VesselData.get() without first invoking .load(), it
will load and parse an internal copy of the stock vesselData.xml from
Artemis 2.1.1.