Remove leading empty lines.

Property definitions

markdown $ MDBlock :: remove_leading_empty_lines
	# Remove leading empty lines.
	fun remove_leading_empty_lines: Bool do
		var was_empty = false
		var line = first_line
		while line != null and line.is_empty do
			remove_line line
			line = first_line
			was_empty = true
		end
		return was_empty
	end
lib/markdown/markdown.nit:1063,2--1073,4