cpp: compat: Update Boost.Endian
cpp: PixelProperties: Use new Boost.Endian native float types
cpp: PixelProperties: Add byteswap helper functions
cpp: VariantPixelBuffer: Remove endian variants
cpp: VariantPixelBuffer: Change spelling of docstring
Merge pull request #1274 from rleigh-dundee/cpp-pixbuf-simplify

cpp: Update Boost.Endian and simplify VariantPixelBuffer