Read markdown lines

Returns an empty array if the Readme does not exist.

Property definitions

nitc $ ReadmeMetric :: md_lines=
	# Read markdown lines
	#
	# Returns an empty array if the Readme does not exist.
	var md_lines: Array[String] is lazy do
		var path = readme_path
		if path == null then return new Array[String]
		return path.to_path.read_lines
	end
src/metrics/readme_metrics.nit:197,2--204,4