Allowing custom Item IDs.
Added a missing comment.
Added help text to subcommands.
Added additional printing for CLI.
Added `doorstop delete ...`.
Renamed `doorstop new` to `doorstop create`.
Merge pull request #96 from jacebrowning/cli

Update CLI: add `delete`, `new` => `create`
Fixed exception publishing empty tree.
Merged 'master' into 'custom-item-id'.
Made the docstring clearer.
Merge pull request #64 from jacebrowning/publish-no-documents

FileNotFoundError: [WinError 3] The system cannot find the path specified
Merge pull request #89 from jacebrowning/custom-item-id

Allow new Item IDs to be set explicitly.
Switch to Python 3 for system install.
Added a failing test to demonstrate the issue.
Added `UnknownItem` to fix publish exception.
Merge pull request #98 from jacebrowning/publish-bad-links

DoorstopError during publish with bad links.
Only adjust level values when empty or modified.
Fixed test name.
Explicitly encoding published files as UTF-8.
Allowing unicode in YAML.