fix: linux views when using modified playspace

[galister]

Closes #2013

What was changed:

• mat3x3 multiplication in OnPoseUpdated was wrong
  • replaced with vrmath::matMul33
  • this alone fixed playspace rotation but only while using standing universe
• do not throw away queued poses when playspace changes
  • with the old logic, there would be ~1s drunken period
  • transition is smooth after the change
• switch to VRApplication_Background
  • this is to get access to GetTrackingSpace() which tells us if the universe is seated or standing
• pull seated or standing transform based on current universe
• handle more events that can cause the playspace to shift
  • previously, it would only trigger on universe change (standing <> seated)
• InitOpenvrClient and ShutdownOpenvrClient are now state-aware
• An automatic recovery mechanism was added that triggers if the reported game_render time goes above 250ms.

Thanks to @Vixea for gathering info & testing

[galister]

Another thing we could add as a safety net is to force a poseHistory->SetTransform(GetRawZeroPose()); when there have been too many consecutive pose history misses, but I haven't run into a case that the current solution didnt't handle.

[Meister1593]

does this fix issue with slimevr, some games like space engine, recenter in steamvr changing playerspace and breaking view completely?

[galister]

the game i tested was subnautica + vr mod, which had a bad case of triggering the issue on the title screen even. recenter and playspace rotate are also fixed. i would think slimevr as well, though i only tested with vive trackers. feel free to test and let me know.

[galister]

note that wlx-s will also need to be updated to support rotated playspaces for space drag, you may get weird results with it as of now

[zmerp]

No concerns style-wise. I haven't tested myself

[Okabintaro]

I can confirm this fixed the issues I had on Subnautica with the SubmersedVR Mod. It's perfeclty playable with ALVR on linux now.