devel/tomlplusplus: add new port
TOML config parser and serializer for C++
Features:
- Header-only (optional!)
- Supports the latest TOML release v1.0.0, plus optional support for some unreleased TOML features
- Passes all tests in the toml-test suite
- Supports serializing to JSON and YAML
- Proper UTF-8 handling (incl. BOM)
- C++17 (plus some C++20 features where available, e.g. experimental support for char8_t strings)
- Doesn't require RTTI
- Works with or without exceptions