- move VPS and related classes into VideoParameterSet.h/cpp
- move SPS and related classes into SequenceParameterSet.h/cpp
- move PPS and related classes into PictureParameterSet.h/cpp
- rename ProfileLevelTier.h/cpp to ProfileTierLevel.h/cpp and move ProfileTierLevel class there

No other changes except for minor formatting/comment cleanup

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

Avoid having a separate PTL count since we already have a size
for the vector containing the PTLs.

Add a size check to avoid writing into inexistant PTL. This may
avoid bug reports such as #1587

Make sure the cofficient size is greater than 0

Includes:
- use of const qualifier
- fix variable naming
- use named constants