Crashes if closed during "Get Psyched" screen while in windowed mode.

[Blzut3]

Original report by Adam Biser (Bitbucket: adambiser, GitHub: adambiser).

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Windows 10 x64

[Blzut3]

Root cause is undefined ordering on exit where the thinker lists may be cleared before the SpawnedActors list is processed. Need to revisit how FinishSpawningActors works.