Read HTTP-request line

		:param request_line: line to parse
			for HTTP/0.9 is GET <Request-URI>
			for HTTP/1.0 and 1.1 is <METHOD> <Request-URI> HTTP/<HTTP-Version>, where HTTP-Version is 1.0
			or 1.1.
			for HTTP/2: binary headers are used

def read_request_line(self, request_line):
		""" Read HTTP-request line

		:param request_line: line to parse
			for HTTP/0.9 is GET <Request-URI>
			for HTTP/1.0 and 1.1 is <METHOD> <Request-URI> HTTP/<HTTP-Version>, where HTTP-Version is 1.0
			or 1.1.
			for HTTP/2: binary headers are used
		"""

		request = self.__request_cls.parse_request_line(self, request_line)

		protocol_version = self.protocol_version()
		if protocol_version == '0.9':
			if request.method() != 'GET':
				raise Exception('HTTP/0.9 standard violation')
		elif protocol_version == '1.0' or protocol_version == '1.1':
			pass
		elif protocol_version == '2':
			pass
		else:
			raise RuntimeError('Unsupported HTTP-protocol')