Moved FreeTrack dependent code to seperate class

This will allow the code to support both FreeTrack and TrackIR without the
code erroring due to one of the two missing.
Updated csproj, added TrackIRUnity.dll

My csproj file is different than pizzaoverhead's due to my local paths
being different. I don't want to mess up his workflow so I will be
manually adding changes to the csproj instead of letting my IDE do it.

TrackIRUnity.dll is from https://github.com/byBrick/Unity-TrackIR-Plugin
Added patched TrackIRUnity.dll to support 64 bit.

Source: https://medsouz/Unity-TrackIR-Plugin-DLL
Recompiled TrackIRUnity.dll for .NET 3.5

Whoops :(
TrackIR SDK support
Merge pull request #1 from medsouz/master

TrackIR SDK Support