Render self as a CsvDocument

Property definitions

nitc $ ReadmeMetrics :: to_csv
	# Render `self` as a CsvDocument
	fun to_csv: CsvDocument do
		var doc = new CsvDocument
		doc.header = metrics_names.to_a

		var metrics = metrics_names
		for mpackage in self.keys do
			doc.records.add self[mpackage].to_csv_record(metrics)
		end
		return doc
	end
src/metrics/readme_metrics.nit:82,2--92,4