Added pyproject.toml.

[benjaminrwilson]

Overview

This PR adds a pyproject.toml file to consolidate styling tools such as isort and black.

• pyproject.toml was introduced in PEP 518 for build system requirements.
• Allows for a unified configuration file for a host of tools, e.g. isort, black, etc.

Each "block" within this file specifies a different type of options. For example, isort is written as:

[tool.isort]

known_first_party = "argoverse"
line_length = 120
multi_line_output = 3
profile = "black"

The options above should have a 1-to-1 correspondence with isort.cfg.

Advantages

• Modern, consolidated project configuration
• Lays groundwork for poetry integration.

[benjaminrwilson]

Removed .isort.cfg since pyproject.toml contains the configuration now.

[johnwlambert]

Hi Ben, does the .toml file change our pre-commit config, or our Tox configuration?

[benjaminrwilson]

None of that should change with this commit. pre-commit doesn't have support (although, it's widely requested) and tox is still defined in a separate file. I suggest nox support in a separate PR.

[johnwlambert]

isort states that .isort.cfg or pyproject.toml are both supported: https://pycqa.github.io/isort/docs/configuration/options/