Append the current line to the last block with the given type,
or create a new one
@param {string} type
@private
function appendLine(type) {
		var len = section.children.length
		if (newBlock ||
			!len ||
			section.children[len - 1].type !== type) {
			section.children.push({
				type: type,
				line: line,
				size: 1
			})
		} else {
			section.children[len - 1].size += 1
		}
		newBlock = false
	}