Major refactor of config classes and config include logic (#214)

**BREAKING CHANGE:** included config now loads envfiles relative to the cwd
specified on the include option (if any).

New/updated special env vars:
- POE_CONF_DIR: the path to the dir containing the config file that defines the
  running task or the cwd set when including the config
- POE_DEBUG makes poe print more stuff to help with debugging

Refactor specifics:
- Introduce PoeOptions class for deserializing config. I would have used
  pydantic but it's too heavy for use in a CLI tool like this.
- Keep config from different files separate within PoeConfig
- Collect config validation logic in the config classes and declare config types
  in more detail
- Make error reporting more structured and consistent

Also:
- Fixed bug that caused some task validation to be skipped for tasks with args
- Improve consistency and coverage for config validation
- Fix crash in switch with args naked string for control
- PoeConfig.load will load everything again if called a second time
- remove pylint from the project
- Enable ANSI color output by default inside GitHub Actions

.gitignore

@@ -1,5 +1,6 @@
 notes/
 tests/temp
+out.txt
 
 # Byte-compiled / optimized / DLL files
 __pycache__/

docs/guides/include_guide.rst

@@ -45,12 +45,21 @@ If an included task file itself includes other files, these second order include
 Setting a working directory for included tasks
 ----------------------------------------------
 
-When including files from another location, you can also specify that tasks from that other file should be run from within a specific directory. For example with the following configuration, when tasks imported from my_subproject are run from the root, the task will actually execute as if it had been run from the *my_subproject* subdirectory.
+When including files from another location, you can also specify that tasks from that other file should be run from within a specific directory. For example with the following configuration, when tasks imported from *my_subproject* are run from the root, the task will actually execute as if it had been run from the *my_subproject* subdirectory.
 
 .. code-block:: toml
 
   [[tool.poe.include]]
   path = "my_subproject/pyproject.toml"
   cwd  = "my_subproject"
 
-The cwd option still has the limitation that it cannot be used to specify a directory outside of parent directory of the pyproject.toml file that poe is running with.
+The directory indicated by the ``cwd`` option will also be used as the base directory for global or task level ``envfile`` imports for tasks defined within an included file.
+
+Tasks and config in an included file can access the ``cwd`` value via the ``POE_CONF_DIR`` environment variable. When no ``cwd`` is set on the include then ``POE_CONF_DIR`` refers the to the parent directory of the config file where a task is defined.
+
+You can still specify that an envfile referenced within an included file should be imported relative to the main project root, using the ``POE_ROOT`` environment variable like so:
+
+.. code-block:: toml
+
+  [tool.poe]
+  envfile = "${POE_ROOT}/.env"