Adds a lint issue to the report. The first arg should be [] of lines on
		which the issue is present. The second arg should be the error message.

def add(self, lines, message):
		"""
		Adds a lint issue to the report. The first arg should be [] of lines on
		which the issue is present. The second arg should be the error message.
		"""
		error = Error(message)

		if error not in self.errors:
			self.errors[error] = []

		self.errors[error].extend(lines)