Is mpackage in its own directory?

Property definitions

nitc $ ReadmeMetric :: has_package_dir=
	# Is `mpackage` in its own directory?
	var has_package_dir: Bool is lazy do
		var path = package_path
		if path == null then return false
		return not path.filename.has_suffix(".nit")
	end
src/metrics/readme_metrics.nit:176,2--181,4