Editorconfig

- lib/ec_glob: Fix potentially uninitialized variable warning.

- Bump CMake requirement to 3.16.3
- lib/ec_glob: plug leak of nums utarray
- Clarify the steps of building from source.

- Fix pointer overflow in STRING_CAT.
- Fix a few more stack buffer overflows.
- Add license for FindPcre2 from LuaDist.
- Document and CI fixes.

- Update property key, value length limits per spec change.
- Fix potential buffer overflow in ec_glob.
- CI fixes.
- Fix paths in pkg-config file with absolute CMAKE_INSTALL_*.
- Fix cross compiling for Windows.

- Fix memory leak in editorconfig_parse() which would occur if no .editorconfig is found.

- Add Windows build scripts.
- Updated AppVeyor to use new scripts.