Release v1.6.1

Release 1.6.1: 22nd August 2024

This release is primarily portability and minor bug fixes.

Changes

• Improve warning levels by the compiler in CI. (#125)

• Switch to GitHub actions for some CI builds. (#121, #123)

• Add configure check for cpuid systems. (#115, #116. Reported by
  Ryan Carsten Schmidt)

Bug fixes

• Use unsigned chars for ctype macros in the name tokeniser.
  On many systems this was already mitigated against, but on some OSes
  a char > 128 could trigger a buffer underrun. (#124)

• Fix interaction between _XOPEN_SOURCE and FreeBSD.
  (#119, John Marshall)

• Improve AVX512 compiler support, notably MacOS El Capitan's XCode.
  (#118, Rob Davies)

• Fix -std=c99 -pendantic pedantry (#117)