Initial support for Tobii EyeX on windows

Note that this requires the Tobii EyeX drivers from
http://developer.tobii.com/eyex-sdk/
Add EyeX to selectTracker sample
Refactor structs in preparation for more
Correct-ish data timestamp delay calculations
Correcting timestamp stuff as close as we can get
Merge pull request #762 from dgfitch/tobii-eyex

Tobii EyeX support