v2.2.4

What's Changed

• Fix: pip install pynec and pip install necpp now work from source distribution without requiring CMake to be pre-run. config.h is auto-generated by setup.py at build time.
• Clean up docs: remove Python 2 references, outdated NEWS, stale install instructions
• Fix necpp README Python 3 syntax in example code

Full Changelog: v2.2.3...v2.2.4