Remove trailing empty lines.

Property definitions

markdown $ MDBlock :: remove_trailing_empty_lines
	# Remove trailing empty lines.
	fun remove_trailing_empty_lines: Bool do
		var was_empty = false
		var line = last_line
		while line != null and line.is_empty do
			remove_line line
			line = last_line
			was_empty = true
		end
		return was_empty
	end
lib/markdown/markdown.nit:1075,2--1085,4