0.4.1 Bugfix Release

Every install run aborted at ddev composer create-project with ".typo3-ddev-setup-marker is not allowed to be present": ddev composer create-project refuses to run unless the project directory is empty apart from a small whitelist, and 0.4.0 wrote that marker file to the project root beforehand. The marker now lives in .ddev/.typo3-ddev-setup-marker - a directory ddev skips over during that check - so it is still written before anything that can fail, and --list/--cleanup keep finding partway-failed runs. Instances created with 0.4.1 are still recognized at the old path (#8).