Firestorm 6.4.21 + P373R VR Mod

Experimental Firestorm Viewer + P373R VR Mod source build

This build includes P373R's VR Mod 6.3.3 changes merged into Firestorm 6.4.21 release branch.

Change Set: Firestorm_6.4.21...humbletim:gha/Firestorm_6.4.21_VR

See https://blog.inf.ed.ac.uk/atate/2021/07/31/firestorm-vr-mod-6-4-21/ for Austin's overview on using VR mode.
See https://gsgrid.de/firestorm-vr-mod/ for more information on Peter's VR Mod.
See https://www.firestormviewer.org/firestorm-release-6-4-21-64531/ for Firestorm 6.4.21 Release Notes

Notes:

• App name has been changed to "FirestormVR" so installation can exist side-by-side with stock Firestorm
  • settings stored in user folder AppData/Roaming/FirestormVR_x64