Drop support for R < 4.1.
Now all functions accept font family name. This is to support TTC file
properly, which contains more than one fonts. A new function dump_fontdb()
is useful to check the actual family name (and the weight and the style) to
specify.
They also accept a file path, so the existing code should work, except when
specifying tolerance
without the named argument.
The minimum supported Rust version is bumped to 1.56.0 for the 2021 edition.
NEWS.md
file to track changes to the package.