Reduce instruction set requirements to plain old SSE.
Check in CMake if selected VC++ version is supported.
Update histogram filter for MT. Small refactorings.
Make focus and grayscale filters re-entrant.
Cleanups
Fix duplicate zero thread id.
Fix MTGuard::EnableMT() working with invalidated script function parameters (fixes mode 2).
Add MT mode getters to some internal filters.
Refactor MTGuard's factory function.
Add new guard to BufferPool to detect metadata corruptions from both directions.
Add AvsAllocType enum.
Make field filters re-entrant. Also mark most as non-cachable.
Merge remote-tracking branch 'main/MT' into filters-mt
Fix env2->Allocate calls (changed API)
Register fps filters for MT. Also replace Visual C++ types with stdint ones.
Make GenericConvolution re-entrant.
Register some simple converts as re-entrant.
Use placement new instead of memset in TemporalSoften. Should be a bit safer.