Add a changelog, detailing notable changes for each release
Search for the correct include and lib directories for the DX SDK

And only set them when needed.
Don't try to include stdalign.h if C11 _Alignas isn't available

Some compilers will allow including stdalign.h, and even define alignas to
_Alignas, even if that C11 feature is unavailable (e.g. because it requires a
suitable -std= setting).
Don't force specific compile flags for the different build types
Use the POSITION_INDEPENDENT_CODE target property when available
Update COPYING to the latest https://www.gnu.org/licenses/old-licenses/lgpl-2.0.txt to fix the FSF' address Fix the FSF' address in the source