=============
- Bump minimum required interpreter version from Python 3.6 to Python 3.8.
- Add ``toolchain download --cross`` feature to allow downloading only the
``rust-std`` (Rust standard library) component of a target. This is useful
for allowing cross-compilation to a given target without downloading the full
native toolchain for that target.
- Update list of supported ``rustup`` targets.
- Note the use of the ``.toml`` suffix for Cargo configuration files.
- Note how to configure Cargo to use the Git command-line client for fetching
the ``crates.io-index`` repository for greatly improved performance.
- Switch to Python Poetry for dependency management.
- Require ``git`` only for operations that need it.
- Tighten command-line argument parsing for shared arguments. Due to an
unfortunate design aspect of Python's ``argparse`` module, "global" arguments
do not work when shared between the main argument parser and subparsers. So,
for example, ``romt --readme`` is accepted and correctly processed, whereas
``romt crate --readme`` is not a syntax error but the ``--readme`` switch is
effectively ignored. There doesn't appear to be a clean way to work around
this, so common arguments are no longer shared between the subparsers and the
main parser. The two main switches (``--readme`` and ``--version``) must be
given before any subcommand, and the remaining switches (``--verbose``,
``--quiet``, ``--num-jobs``, and ``--timeout``) must be given after the
subcommand name (e.g., ``romt crate --verbose``).
- Allow environment variable ``RUSTUP_DIST_SERVER`` to override default value
for ``romt toolchain --url``. Allow environment variable
``RUSTUP_UPDATE_ROOT`` to override default value for ``romt rustup --url``.