Changes include:
- use [[maybe_unused]] instead of cast to (void)
- use generic lambda function and remove related comment about C++11
- update MSVC version check
- don't condition '#pragma once' on MSVC version

This reverts commit 9eca063e.

The fix was confirmed as part of the specification.

Software implementation for N0278:
1. Added VPS encoding in encoder
2. Add new project StreamMergeApp to N-to-1 bitstream merge
3. Changed decoder to support only decoding the specified layer stream

There should be no limit on the number of NAL units output when
m_numNALUnitsToWrite is set to -1

- remove HighPrecision MV option
- fixes for statistics output
- removal of SVN header integration (fixes issue with Xcode)