adhere to the os.popen convention.  Improved documentation.

code -- use testdriver.py to run the tests instead.
(TestSpawn): Inherit from test.base.TestCase.
(TestSpawn.test_spawn_sleep_1): Use assertTimeDiff instead of
	assertAlmostEqual.
(TestSpawn.test_spawn_sleep_1_compat): Ditto.
(TestSpawn.test_hello_world): New test.
(TestSpawn.test_stderr): New test.
(TestSpawn.test_stderr_2): New test.

code -- use testdriver.py to run the tests instead.
(TestPopen): Inherit from test.base.TestCase.
(Timeout): Moved to test/base.py.
(handler): Ditto.
(TestPopen.setUp): Moved to test.base.TestCase.
(TestPopen.tearDown): Ditto.
(TestPopen.test_popen_sleep_1): Use assertTimeDiff instead of
	assertAlmostEqual.
(TestPopen.test_popen_sleep_1_compat): Ditto.
(TestPopen.test_read_hello_no_eof_handling): New test.
(TestPopen.test_read_hello_no_eof_handling_no_exception): New test.

(handler): New signal handler.
(TestCase): New class.
(TestCase.setUp): New setup function.  Reset the state of pcl_expect,
	and set up a SIGALRM timer.
(TestCase.tearDown): Cancel the SIGALRM timer.
(TestCase.progress): Re-arm the SIGALRM timer.
(TestCase.assertTimeDiff): New function.

Add more documentation.

(TcpBase): New class.  This contains most of the old Tcp class,
	except for the socket creating and connecting code.
(Tcp): Renamed to TcpBase.
(TcpClient): New class.
(TcpClient.__init__): New method.

exceptions.

	constructor call.

API.

(stty_init): Change default value to False instead of None.
(__use): New function.
(_inherit_stty): New function.
(_stty_init): New function.
(_spawn): New arguments: inherit_stty, stty_init.  Only inherit
	stty settings if stdin is a tty.  If an exception occurs in
	the child, transfer it to the parent as a
	remote_exception.Remote object.
(Spawn.__init__): New optional arguments: inherit_stty, stty_init.
(spawn2): Pass all arguments to the Spawn constructor.

(Remote): New class.
(Remote.__init__): New method.
(serialize): New function.
(re_raise): New function.

input from the serial port.