Poethepoet

Enhancements
- Improve support for windows in general
- Shell tasks can run on windows if a suitable bash executable (such as git-bash or wsl bash) can be found

Breaking changes
- Drop support for the `run_in_project_root = false` global setting

Implementation changes
- Drop direct dependency on poetry
- Use the `poetry run` cli for running tasks from outside of the poetry shell

- Add support for specifying environmental variables for a task
- Add support for specifying a help message per task

- Add support for python __script__ tasks
- Add support for __shell__ script tasks
- Add config option to change the default task type

Major code refactor and new features including:
- Ensure poetry environment is available to tasks without poetry run/shell
- Add support for --dry-run cli option
- Add support for escaping shell variables to they're passed to the task
- Make UI method respect the reduced verbosity level set via -q.
- Add --version option to cli

First *fully usable* release including error handling and help messages.