Tracking is sometimes disabled when using FreeIVA

[brianmwaters]

As mentioned in #1, when using FreeIVA and KerbTrack at the same time, you can run into an issue where head tracking stops working.

To reproduce, install FreeIVA, and enter IVA mode with head tracking. Observe that head tracking is working normally. Now, press Y to step out of the chair, and move around a bit. (Note that head tracking does not work in this mode, probably because it hasn't been implemented.) Now, re-enter the chair. Note that head tracking now no longer works when the game is running, but only when the game is paused.

As a side-issue to this, it would be neat to get head tracking working while the character is moving around freely in FreeIVA, but I'm not sure what would go into that.